nr. 3 EN/2011

SUMMARY

Florin BACIU, Victor ARAD, Susana ARAD, Susana IANCU (APOSTU) Ecological rehabilitation of Sfântu Gheorghe and Bodoş open pits 2

Doru CIOCLEA, Constantin LUPU, Ion TOTH, Ion GHERGHE, Cornel BOANTĂ New technology implemented in the settling of complex ventilation networks 7

Florin G. FAUR Developing a new methodology for calculating reliability marks for environmental factors (water) 11

Carmen Georgeta FLOREA, Adrian Alexandru DRESCHER, Vlad Alexandru FLOREA Determination of possibilities of the active lateral earth pressure on abutment walls of enlarged roadways 17

Dumitru IACOB Technical aspects of the distribution joints from E.M.C. Jilţ 22

Dacian Paul MARIAN, Ilie ONICA, Eugen COZMA Sensibility analysis of the subsidence parameters at the variation of the main geo-mining factors 28

Alin Cosmin SMEU Achievements and future solutions on reintroducing in the economic circuit of waste dumps and degraded terains by open pits from oltenia 35

Vasile ZAMFIR, Horia VÎRGOLICI, Olimpiu STOICUŢA The positional synthesis of the slider-crank mechanism 43

UNIVERSITATEA DIN PETROŞANI 20 University Str., 332006, Petroşani, Hunedoara county

Information: phone 0254 / 542.580 int. 296, fax. 0254 / 543.491 Bank account: RO91TREZ368504601X000062 C.U.I. 4374849 Trezoreria Petroşani

e-mail: [email protected], [email protected] www.upet.ro/revista/revistaminelor.html

The papers must be sent to one of the addresses above, together with an abstract and four keywords. The responsibility for the content of the article belongs to the authors.

Unpublished papers will not be returned. © Copyright Revista Minelor 2011 – appears quarterly

UNIVERSITAS Publishing Petroşani

ISSN 2247 -8590 ISSN-L 1220 - 2053

Revista Minelor – Mining Revue is accredited by the National Council of Scientific Research from Higher Education (CNCSIS) cathegory B+

Revista Minelor – Mining Revue is indexed in the EBSCO Publishing database U.S.A.

http://www.ebscohost.com/titleList/a9h-journals.pdf

Editor: Ec. Radu ION Printed at: University of Petroşani – Printing Department

ECOLOGICAL REHABILITATION OF SFÂNTU GHEORGHE AND BODOŞ OPEN PITS

Florin BACIU*, Victor ARAD**, Susana ARAD***, Susana IANCU (APOSTU)****

Abstract: Exploitation of mineral resources in quarries, lead major changes in surface and consequently a major impact for the population. In some cases the stability of soil or construction may have catastrophic effects. Thus rehabilitation of land affected and reduce or eliminate the effects of pollution are major problems in the closure of mining activity. For this purpose it is necessary to achieve ecological rehabilitation measures for the affected areas. Present research is a summary of a comprehensive study related to mine closure activity in the SNC Ploiesti.

Key words: coal, quarries, mine closure, stability, environmental rehabilitation Introduction

National Coal Society S.A. Ploiesti was set up by reorganization of Autonomous Administration of Coal Ploiesti which was abolished in 1997. Today eight mine exploitations situated in eight districts are part of it and it ensures the power coal necessary for the thermo-electric power stations from Bacău, Braşov, Zalău and Oradea.

At the moment most of the underground exploitations are closed, except from Jugur sector from Câmpulung area, Argeş County. Aninoasa, Argeş County, Racos from Covasna county open pits and Filipeşti and Ceptura from Prahova county open pits are also part of the exploitation.

As far as the environmental impact is concerned, the most productive coal-wise lignite open pits through time were the two subunits in Covasna County, Sfântu Gheorghe and Bodoş open pits.

Mining objectives closure and ecological reconstruction of the exploitation affected areas activity is one of the most complex activities after mining and exploitation of mineral resources [1]. Bodoş and Sfântul Gheorghe open pits were surface lignite exploitation units, being set up in 1987. Because of the economical inefficiency ____________________________________ *Director SNC Ploieşti **Prof.eng.Ph.D University of Petroşani *** Assoc.prof.eng Ph.D University of Petroşani **** Ph.D student Universitatea din Petroşani

mainly due to the poor quality coal exploited production stopped at the end of April 2004. The total volume of the stripping is 16 millions m3 and the exploited production is 2.000.000 tones of lignite which was used to produce electricity and heat homes.

Ecological rehabilitation of the areas affected by lignite exploitation from Bodoş and Sfantu Gheorghe open pits aims to re-establish the ecosystems structurally and functionally as well as to ensure the abiotic and biotic resources necessary for sustainable development. Geology of the area

Baraolt post-tectonic sedimentary basin has a relatively complicated geology because of the basin building-up geo-tectonic processes and further coal carrying strata driven processes as well as specific deposition processes that generated coal layers storage. The mining area is located in the southern extremity of Barsa depression, formations consisting of molasses deposits with Pliocene-Pleistocene coals which are on top of Cretaceous flysch deposits.

The deposit is composed of ten variable thickness and extension coal layers determined by deposition conditions and Cretaceous bedding configuration.

The proper coal-bearing complex is characterized by an interchange of grey sands, sometimes andesite, yellowish grits, tufaceous clays, coal-bearing clays, purple or green-blue clays and coals. Within the subsystem, the three coal layers are composed of multiple layers, being solid only rarely. Only layers I and III have economical value. This subunit is from the Late Pontian age. Layer III is the layer with the maximum growth in the basin, being 2-8.6 m thick and it is situated 8-130m deep in the roof of layer I [3]. The impact caused by the exploitation Bodoş open pit abolishment does not have a major socio-economic impact because the majority of the staff has been redistributed to Racoş-Sud open pit, an open pit that is productive.

2

Revista Minelor - Mining Revue no. 3 / 2011

By abolishing Bodoş and Sfântu Gheorghe open pits it has been achieved:

Disposal of the noise in the area produced by typical machinery in the open pit and on the road leading to it that crosses Bodoş village.

Disposal of the dust in the air produced in the open pits, waste dumps and on the road

Disposal of solid suspensions from the streams next to the open pits and the waste-dumps

Re-establishment of the natural aspect of the areas affected by open pits and waste-dumps and improvement of the surface soil,

Re-establishment of the natural aspect will take into consideration the wooded areas before opening the quarries as well as the mainly hay tamed areas Coal exploitation in the open pits has produced and will produce an impact caused by used industrial and domestic water evacuated from the open pit, an impact produced by water management and an impact produced by dewatering produced water evacuated from the open pit.

Transporting coal on the exploitation road and on the public road has affected the infrastructure of the public road, damaging the bridge over Baraolt brook, damaging the guard ditches, the public road, dust suspensions air infestation and damaging over 80 ha of land which will be subject to modelling and greening.

Lignite exploitation in the open pits affects the qualities of environmental factor air by dust, smoke and gas emissions.

Sources of dust emissions are coal deposits, deposits of waste rock from the damp, excavation areas, access roads from the waste-dumps and the open pits as well as the slopes and open pits terraces, open pits affected by climatic factors and uncovered by vegetation. Air pollution in these areas is a physical one.

Auto-ignition of coal from the open pit slopes or deposits emits fumes and pollutants that are spreading into the atmosphere. The impact of coal mining activities on the soil and subsoil is both qualitative and quantitative.

Quantitative impact on the ground translates into open pit, external waste-dump, utilities, land with permanent or temporary productive, agricultural or sylvan circuit removal employment, fig 1.

Another form of manifestation of the impact is the change of the terrain features in the natural area which has objectified through other forms of terrain. Qualitative impact is manifested by destroying the natural geo - lithology of the land up to more than 150 m deep due to stripping work for coal extraction.

Fig.1. The impact on the soil

The impact on the soil in the area is manifested

by physical pollution with coal dust and sterile as well as by erosion and landslides which leads to decreased fertility of the surrounding areas.

It can be concluded that the main and auxiliary activities carried out in the open pits have had a major negative impact on the environment as a whole, changing the relations between environmental components on a 300 ha area almost completely. Ecological rehabilitation of Bodoş and Sfantu Gheorghe open pits Abolishment and economic restructuring of lignite exploitation is one of the present subjects of the Romanian mining industry which tries to comply with the EU requirements.

The restructuring process began after the ‘90s, when the World Bank demanded, being actively involved in this economic field [2].

After 1989 the energy sector has been intensely supported by the state through a big budgetary effort, the state spending large amounts of money through grants, transfers and capital allowances. Unfortunately, budgetary funds were insufficient and because of keeping energetic coal selling price low there were registered operating losses at most of the mines [1].

The area covered in this paper is situated within the area of Baraolt city, from Bodoş village border and the plots to be wooded before expropriation have been taken by the former Baraolt forestry-Covasna forestry department.

Technical-economic indicators are presented in Table 1 [3].

Table 1 Technical-economic indicators Indicator Value Total area under study St = 16,61 ha Actual area to be forested Se = 16,61 ha Hedge against grazing LG = 2650 m Time of deployment T = 7 years

3


The aims of the works are: Reseating forested vegetation on the former

open pit waste-dumps Improving climatic conditions Restoring ecological balance in the area by

restoring the biodiversity Improving the local and general landscape.

The areas covered by the mining exploitation perimeter as well as those surrounding them that bear the “imprint” of exploitation in the open pit and that don’t require remodelling will undergo rehabilitation and greening so that they can reach agricultural yield at the level they had before being affected. Bodoş open pit ecological rehabilitation works [3]

Production in the open pit ended in late April

2004 due to economic inefficiency, the main factor being the poor quality coal exploited; at the time of the closure, Bodoş open pit had debts of 45.057.973.544 lei.

Once production stopped, all machines and facilities in the open pit were removed and redeployed to Căpeni Colliery.

The technical project on closing and cleaning Bodoş open pit has been achieved through a number of works to ensure safety and stability of the area and at the same time greening of the area, restoring the areas occupied by the open pit and its external waste-dump to the agricultural and forestry chain [5].

Within the project a barrier lake was built, three spaces in the open pit were decommissioned, rehabilitating the access road that had served exclusively the open pit as well as the LEA power line that had supplied machines in the open pit. Stopping activity in the open pit coincided with stopping discharging water from its floor.

The lake that will store the waters will be north-east and south-west oriented. The barrier lake will be 295 m long at the water gloss level and will be 30 m wide at the bottom of it. The slope angle of the walls will be 12 degree. Rock material resulting from excavation was necessary remodelling surface. To ensure stability, 20m wide of the west side of the shaped area as well as the 370m length will be covered with acacia. Reshaping the surface runs at the same time as the geometrization of the external waste-dump, the embankment and reshaping material used for this is the excess of earth from the waste-dump.

The reshaped surfaces of the open pit and the waste-dump will be wooded, which will re-establish the slopes and wooded areas destroyed by lignite exploitation.

The already existing waste-dump need backfilling works – excavation, fertilization and grassing. The excess rock is the material necessary for remodelling the area occupied by the open pit. Together with reshaping the sterile waste-dump an 80 m long supporting wall will be built on the eastern slope of the waste-dump.

The channels following the roads will be resized according to the maximum flow of the rain waters and will be clad with concrete tiles. Their total length will be 14.000 m, fig. 2 [4].

Fig.2. Channels collection

Reconstruction of the public road on the

section which was used by Căpeni Colliery to transport coal from the open pit and machines and materials to the open pit throughout the active period, the total length of the road sector being 7,5km.

As a result of the intensive lignite exploitation and transport on the initial bridge, it collapsed therefore needing repetitive constructive interventions which failed to achieve their aim.

In the same location but oriented perpendicular on Baraolt stream a bridge has been built, taking into account: the opening of the stream in the established location, 20 m; the daily and annually flow of vehicles; gauge of vehicles; maximum tonnage of the biggest vehicle; fig. 3.

Fig.3. Sight on bridge

Baraolt riverbed rehabilitation will consist of:

dredging riverbeds, changing Baraolt river course where the old bridge used to be. The total costs of

4


environmental rehabilitation of Bodoş open pit are 14.206.391.90 lei. Closing and ecological activity on Sfantu Gheorghe open pit [4] Ecological activity of the open pit requires maintaining the ecosystems formed by accumulations of water from Porumbele waste-dump area with flora and fauna and using the affected areas as place of leisure.

Partially filling of the former open pit and building a leisure lake of 27 ha are part of the project objectives. Partially discarding of Porumbele waste-dump is made by transporting a volume of 6.170.000 m3 of sterile in the open pit. Arranging and greening of the open pit involve three steps: step I: geometrization of open pit floor; step II: lake formation; step III: slope grassing and foresting. Geometrization of the open pit floor involves entrapping and conducting all water inflows, groundwater and surface water towards a central sump hole which will supply the lake, fig. 4.

Fig.4. Open pit aspects

These works consisted of entrapping the brooks

in the western, north-western and southern areas by executing artesian bore in order to allow the geometrization of the open pit floor and backfill and water storage to shape the future lake.

Earthmoving and geometrization works of the open pit will be performed, followed by its backfill by arranging the final slopes of the future lake and its surroundings.

The works consisted of open pit floor backfill up to the established level for the bottom of the lake set for 550m and the slopes by transporting material from Porumbele waste-dump, spreading and tamping it at 95 tamping level [6].

The open pit slopes are designed at an angle of maximum 9° in order to ensure their stability. Backfilling of the floor and the slopes is made by depositing material in layers of 30 cm with their

leveling and compacting at a compacting level of 95%.

The lake is filled with water from Crişului Valley and a water intake will be made on Crişului Valley and an adduction which will supply the future lake at a 5m 3/h rate. The discharge channel is underground, made of 1,400 mm diameter pre-stressed concrete pipes on the lake- Crişului Valley route on a 1,047m distance. A technological road will be built to ensure lake maintenance and supervision after putting it into operation.

Grassing and foresting the slopes means laying topsoil extracted from the topsoil waste-dumps, 30 cm thick, on the open pit slopes from the level representing the future water gloss at a level of +560 to the open pit frame at a level of +570.

Arranging the southern flank will consist of surface reconfiguration so as not to carry large amounts of mining mass from Porumbele waste-dump but to reshape the southern flank slope by rock dislocation from the external side of the open pit and filling the gaps at the edge of the slope.

The excavation volume needed to bring the slope to a 90° angle from level +570 to level+ 560 is 249.903 m3 and the filling volume is 393.875 m3. The difference will be brought from the Porumbele Valley topsoil waste-dump.

An perimetric access road will be built at the southern border of the open pit on private lands, being 5m wide and having 5 m wide safety pillar to allow access to earthmoving machines, needed to arrange the southern flank and to store fertile soil and for owners to access the play areas, fig. 5 [4].

Fig.5. The road for perimetric access

The sterile waste-dump will fuel with mining

mass the difference of material necessary to build the southern and south-eastern flanks.

The difference of sterile which will not be needed for this reconstruction but will remain inside the waste-dump will be spread evenly on the south-western versant of Porumbele Valley. After the geometrization of the Porumbele waste-dump,

5


the surface will be covered with topsoil from the topsoil deposit and after that it will be sowed, continuing work at the now running waste-dump.

After rearrangement, a 455,750 m2 surface will be replaced in the economic chain. 67,900 m2 of the surface will be covered with saplings. Rearrangement of the southern flank was designed to run on a 269,783 m2 surface. After being arranged and covered with vegetal soil, 50,272 m2 will be issued to be used by the old owners.

Next, for a 209,711 m2 surface, greening operations are set to run over three years. These operations will consist of fertilization of the land, sowing perennial grass and Orchard saplings.

Total costs of Sfantu Gheorghe open pit rehabilitation is 72,442,471.93 lei [6].

Conclusions

In accordance with the Environmental Law, when the open pits stop functioning there have been identified the following effects of the impact on the environment: The decisive impact has been on the ground by completely modifying the ground morphology of the entire 106.6473 ha area. Besides direct influences soil has been affected by the emergence of phenomena of material flow in the slopes with a modified balance by stripping and mining activities. Sterile deposits in the waste-dump have been made within parameters which gave a temporary stability. Failing to follow the waste-dumping parameters has led to downstream sterile material spills in certain areas. If in the exploitation area the vegetation was completely destroyed, in the surrounding area vegetation and fauna have been affected to a smaller extent by deposits of sediment, and as for the fauna by anthropical impact. Emergence and development of the exploitation has led to social-economic changes in the area, which require a coherent professional reorientation programme once the exploitation activity has stopped, which consists of redistributing staff to Racoş Sud open pit.

As a result of thorough research on the analysis area in terms of geographical location, impact of

mining in Bodoş and Sfantu Gheorghe open pits on the area, economic, social and environmental factors, existing circumstances, in order to integrate relevant elements in the sustainable circuit of area development all the measures in the project will be applied and will be adapted where there are inconsistencies.

In order to eliminate lignite exploitation effects, prevent water storage and landslides, the areas affected by the open pit and the waste-dump will be reshaped.

Destination of areas after reshaping and cleaning: 18,064 m2 for the barrier lake; the forested areas after reshaping make 79,673 m2, the access road to the remodelled and cleaned areas of the open pit make 1,725 m2. On a 355,957m2 surface the former open pit as well as large eastern and western reshaped areas will be grassed. References 1. Arad, S., Arad, V., Nistor, C., Baciu, Fl., Nita, A. Predicting ground mouvments in post mining activity from Romania, Proc. of 5 th Conf. On Environment and Mineral Processing, Part II, VSB TU Ostrava, pp. .59- 67, ISBN 978-80-248-2388-1, Ostrava, Czech Republic, 2011

2. Arad, S., Arad, V., Chindriş, Gh. Geotehnica mediului, Ed. Polidava Deva, ISBN 973-99458-0-5, 232 pg., 2000

3. Baciu, Fl. Impactul asupra mediului a exploatărilor subterane şi la zi aparţinând S.N.C. Ploieşti, Raport de cercetare, Univ. din Petrosani, 2010 4. Baciu, Fl. Cercetări privind stabilitatea structurilor de suprafaţă: taluzuri, halde, versanţi din zonele miniere aparţinând S.N.C. Ploieşti, Raport de cercetare, Univ. din Petrosani, Raport de cercetare, Univ. din Petrosani,2010 5. *** Proiect tehnic de inchidere si ecologizare a Carierei Bodos, EM Capeni, 2007 6. *** Proiect tehnic de inchidere si ecologizare Cariera Sf.

Gheorghe, Halda Porumbele, 2009.

6


NEW TECHNOLOGY IMPLEMENTED IN THE SETTLING OF COMPLEX

VENTILATION NETWORKS

Doru CIOCLEA*, Constantin LUPU*, Ion TOTH*, Ion GHERGHE*, Cornel BOANTĂ*

For providing the best possible occupational health and safety conditions for the staff working in potential explosive and/or toxic atmospheres, there are used special ventilation installations. For the case of underground operations, this aspect is quite complex because the ventilation network covers tens of kilometers. Also, the mining network is in a continuous change and consequently, the distribution of air flows along each branch is quite difficult to be made. The settlement of ventilation networks with the help of classical methods needs a lot of time and is difficult to be implemented; nevertheless the use of new methods, for ex. of new expert software, represents an accessible option. In order to settle the ventilation network related to Paroşeni mine, there has been used a Canadian expert software called CANVENT; as a result, there was settled both the basic network and there were simulated certain possible technical conditions that involved major changes regarding the distribution of air flows. This paper presents both the specific elements regarding the settlement of the ventilation network and the above said simulations General notes The mine network necessary for the mining of useful mineral substances displays a high complexity, different shapes and cross-sectional areas and can reach tens of kilometres in length. For getting the best possible working conditions in underground, it is necessary to provide the primary protection, i.e. suitable ventilation [3] . The purpose of this ventilation is to: - provide the concentration in oxygen necessary for the personnel currently working underground; - dilute the explosive and/or toxic gases existing in the mine network; ____________________________________ *Ph.D eng. INCD INSEMEX Petroşani

- diminish the heat emitted inside mine workings, both due to human activities and to thermal gradient. A good ventilation of each mine working involves the best possible repartition of air flows along each branch of the ventilation network [4]. In this spirit it is necessary to settle the ventilation network of each mine. An example of complex ventilation network is the one belonging to Paroşeni mine. Analysis of the ventilation network belonging to Paroşeni mine and measurements carried out in situ The general ventilation of Paroşeni mine is of the upward type, under the influence of the depression s created by the main ventilation station no. 18 VOD 30. At Paroşeni, coal is extracted through four workings: - face working panel 4, bed 3, block VI level 300; - face working panel 24, bed 3, block V level 250; - working with short face (pillar), bed 3, block V level 250; - working with short face, panel 3 bed 3, block V level 250. According to the annual project for general ventilation for the second, third and forth trimesters that takes into consideration the structure of the ventilation network, the dispersion of the working faces in operation, as well the operation of the main ventilation station no. 18 VOD 30, there have been devised three main ventilation circuits: - the ventilation circuit of the level 250; - the ventilation circuit of the level 300; - the ventilation circuit of the level 360. In order to find out the real values of the aerodynamic parameters specific to the mine workings that are part of the mine ventilation network, there have been carried out measurements of the air flows and of the depressions. The whole ventilation network includes 171 junctions (knots) and 216 branches [2]. Settling the ventilation network of Paroşeni mine For providing the best solution available for such a complex ventilation network, we have used

7


the Hardy-Cross method for successive approximation. This method represents the grounds of expert software CANVENT designed in Canada [1]. 3D – CANVENT is a Window type application and it has been designed to support the planning, design and analyze the mine ventilation systems. 3D – CANVENT represents a mixture between a friendly use of graphic representations and the capability to design 3D networks that makes possible to visualize the ventilation network in a 2D system (X–Y, X–Z, Y–Z) and/or 3D system (X–Y–Z). This software helped us to provide the solution for the ventilation network as well an optimization of the air flow distribution within the ventilation branches. Settling the ventilation network of Paroşeni mine made necessary to run several stages: • Marking the junctions of the ventilation network on the spatial diagram; • Determining the geodesic coordinates of the identified junctions and inputting the geodesic coordinates of junctions and the existing branches into the database of the software (see Fig. 1).

Fig.1. Table with knots

• The carrying out of measurements in situ; these measurements include:

- measurements of the aerodynamic parameters of mine workings;

- measurements of the geometrical parameters of mine workings;

- measurements of the physical parameters of the air;

• Calculation of aerodynamic strength specific to each branch and the inputting the values of parameters specific to the ventilation network into database (see Fig. 2);

Fig.2. Table with branches

• The 2D or 3D drawing of the ventilation network; • Settling the ventilation network. Both the direction and the optimum distribution of the air flows along each branch are being identified in this stage (Fig. 3).

Fig. 3.

Modeling / simulations in the general ventilation network of Paroseni mine made with the help of 3D CANVENT software

With the view to evaluating the future changes that may come up in the mine general ventilation network in relation to the distribution of the air flows [2], both from the point of view of their size and direction, the locations of the structures for the control and drive of air flows, as well the types of mine ventilation structures, there have been settled, in full agreement with the department for occupational health and safety at Paroseni mine, the following simulations: Simulation no. 1 – Settling the ventilation network with the change of the route used to discharge the poisonous air on the new inclined plane Panel 4/3/VI level 300, implicitly of the related ventilation structures. Simulation no. 2 – Settling the ventilation with the opening of a group comprising 3 air doors at the level 250, at the base of the ventilation rise 250 – 360. Simulation no. 3 – Settling the ventilation with the opening of a group comprising 3 air doors at the basis of the behind shaft 360 – 575. Simulation no. 4 – Settling the ventilation with the opening of a group comprising 3 air doors at the connecting gallery no. 4, between the west longitudinal way level 250 and the conjugated ventilation longitudinal way level 250. There follows the presentation of results gained after performing two of the above-said simulations (i.e. simulation no. 1 and simulation no. 4).

8


Simulation no. 1 – Settling the ventilation network with the change of the route used to discharge the poisonous air on the new inclined plane Panel 4/3/VI level 300, implicitly of the related ventilation structures

There have resulted the following aspects after the simulation no. 1 (Fig. 4):

Fig. 4.

– There has been a significant change in the distribution of the air flows inside the ventilation network of Paroşeni mine, especially within the mining area related to the block VI; subsequently, the flow rate diminished from12.61 m3/s to 1.29 m3/s at the face no. 4/3/VI; – As a result of settling the ventilation network (after the location of 5 ventilation structures), there resulted a distribution of the air flows almost similar to the distribution of air flows at the basic model, except the flow rate gained at the face panel 4/3/VI where it diminished from 12.6 m3/s to 10.97 m3/s; – A diminution of the annual costs related to air conveyance along the blind shaft (branch 156-159) with 3.82% from 387,019 lei to 372,219 lei; – An increase of the annual costs related to air conveyance along the air way W that connects to the blind shaft level 360 (branch 100-155) with 7.73%, from 3,168 lei to 3,413 lei, – A diminution of the annual costs related to air conveyance along the air way that connects to the blind shaft level 425 (branch 154-156) with 24.91%, from 562 lei to 422 lei; – There has been registered a diminution with 3.53%, from 95,519 lei to 92,150 lei for the ventilation canal of the main ventilation station no. 18 VOD 3.0 (branch 159-160); – There has been registered a diminution of the annual costs related to air conveyance with 0.35%, from 1,118,298 lei to 1,114,401 lei for the whole main ventilation station no. 18 VOD 3.0.

Simulation no. 4 – Settling the ventilation with the opening of a group comprising 3 air doors at the connecting gallery no. 4, between the west longitudinal way level 250 and the conjugated ventilation longitudinal way level 250 Simulations no. 4 relied on the simulation no. 1 and it comprised a removal of the air doors located on the connecting gallery no. 4 between the longitudinal way W level 250 and the conjugated ventilation longitudinal way level 250, branch 48-55 (Fig. 5). There have resulted the following aspects after the simulation no. 4: – The distribution of the air flows in the ventilation network of Paroşeni mine didn't change significantly for the ventilation circuit panel 1/3/V level 250; there were moderate changes for the face panel 4/3/VI, where the air flow rate diminished from 12.61 m3/s to 10.89 m3/s and for the face panel 2/3/V where the flow rate diminished from 19.02 m3/s to 17.2 m3/s. The distribution of air flows changed significantly for the ventilation circuits panel 1/3/III level 250, where the air flow rate diminished from 13.57 m3/s to 4.47 m3/s; – A diminution of the annual costs related to air conveyance along the blind shaft (branch 156-159) with 2.72% from 387,019 lei to 376,492 lei; – An increase of the annual costs related to air conveyance along the air way W that connects to the blind shaft level 360 (branch 100-155) with 10.48%, from 3,168 lei to 3,500 lei; – A diminution of the annual costs related to air conveyance along the air way that connects to the blind shaft level 425 (branch 154-156) with 26.3%, from 562 lei to 414 lei; – There has been registered a diminution with 2.51%, from 95,519 lei to 93,120 lei for the ventilation canal of the main ventilation station no. 18 VOD 3.0 (branch 159-160); – There has been registered a diminution of the annual costs related to air conveyance with 0,25%, from 1,118,298 lei to 1,115,557 lei for the whole main ventilation station no. 18 VOD 3.0.

Fig. 5.

9


Conclusions • For modeling the ventilation network of Paroşeni mine, there has been used the iterative method of successive approximations; the whole software for settling the ventilation networks (3D - CANVENT) relies on this method. • The elements necessary to run the software (i.e. the inputs) are gained after monitoring the ventilation process. • Based on the current ventilation network, there have been determined the simulations of possible situations. • The simulations have underlined both the important part played by the group of air doors and their influence over the distribution of air flows at each branch. • Each simulations intended to acquire the necessary flow rates in accordance with the Annual ventilation project, measured at faces of the main ventilation circuits and at the main ventilation station. It has to be stipulated the type of control and/or regulating structures, as well their locations in order to be able to reach the desired distribution.

• For each simulation, there has been determined the operating mode of the two fans at the main ventilation station no. 18 VOD 3.0; these simulations have also allowed to evaluate the ventilation capabilities of the mine for each situation apart. References 1. Canvent Mining and Minerals Sciences Laboratories Underground Mine Environment and Ventilaţion, Manual de utilizare – program 3D –CANVENT -2K 2. Cioclea D. ş.a. Diminuarea riscurilor generate de atmosfere explozive prin utilizarea tehnicii de evaluare în timp real a reţelelor de ventilaţie în vederea protecţiei factorului uman, Studiu INCD-INSEMEX 2008 3. I. Matei, G. Băbuţ Ingineria mediului şi ventilaţia în subteran, Editura Tehnică Bucureşti – 2000 4. x x x Environmental Enginering in South African Mines, The Mine Ventilaţion Society of South Africa -1989

10


DEVELOPING A NEW METHODOLOGY FOR CALCULATING RELIABILITY MARKS FOR ENVIRONMENTAL FACTORS (WATER)

Florin G. FAUR*

Abstract: This paper proposes developing a new methodology for calculating the reliability marks given to environmental factors (used in the procedure of environmental impact assessment through global index) which takes into account issues such as toxicity of pollutants, the probability that they reach dangerous concentrations in environmental compartments, etc. The paper should be regarded as a proposal and it should be noted that the calculation refers only to reliability marks for water. Keywords: impact assessment, reliability marks, indicating parameters, weighting factors. Introduction

One of the most important environmental protection activities is to evaluate the impact of human activities on the environment. This activity is particularly important in Romania, currently regulated by Government Decision 1213 of 06.09.2006 (with amendments and subsequent additions, replaces GD 918 from 2002 which in turn replaced the Order 125 of 1996) and establishes the overall procedure for environmental impact assessment.

Although environmental impact assessment is a legally regulated activity for 15 years, a common feature of normative acts mentioned above is the lack of establishing a (some) ways to perform this assessment.

In the absence of such published methods, in Romania, are used a range of methods taken from Western Europe and the U.S. (impact matrix, impact networks, thematic maps, checklists, etc.). This methods can sometimes be difficult to understand (especially if we consider public participation in the evaluation of environmental impact) or can be used wrongly.

But there is a method, often used nationally to assess the impact, which is more accessible and understandable to the general public, namely the method for assessing the overall pollution (impact) index. ____________________________________ * Ph.D eng. University of Petroşani

Presentation of overall pollution index method Thus this method considers that the aim of

assessing the impact of human activities on the environment and the evolution of the phenomenon of pollution requires a comprehensive assessment of environmental pollution at a time.

Such an assessment would allow a mapping on a regional - macro-regional level in terms of environmental quality status.

In general, it is considered possible to appreciate the environmental quality of an area and at a time by:

Air quality; Water quality; Soil quality; State of flora and fauna of the area; The health of the population in the area; Landscape. Each of these factors is characterized by

representative quality indicators for assessing pollution and for which there are established acceptable limits (MAC). Depending on the enrollment in the normal range reliability marks (RM) are given.

Ideal state is represented by a regular geometric figure that circumscribed circle radius passing through the polygon vertices are divided into ten units of reliability, counting from the center of the circle.

By joining points from location expressing the true state values, an irregular geometric figure is obtained with a smaller area, which is submitted to the regular geometric figure representing the ideal status.

The global pollution (impact) index of an ecosystem (IPG) results from the ratio of the surface representing the ideal state (Si) and the surface representing the real condition (Sr):

IPG = Si / Sr When there are no changes in environmental

quality, so when there is no pollution, this index is equal to 1.

Conventionally a scale from 1 to 6, for overall pollution index, was established as follows:

IPG = 1 - natural environment unaffected by human activities;

1 <IPG <2 - environment affected by human activities within reasonable limits;

11


2 <IPG <3 - environment affected by human activities causing discomfort for life forms;

3 <IPG <4 - environment affected by human activities causing disorders for life forms;

4 <IPG <6 - environment severely affected by human activities, dangerous for life forms;

IPG> 6 - degraded environment, inappropriate for life forms [1].

The method can be used in any of the phases of a project, environmental quality assessment before starting a anthropogenic project, environmental quality assessment during the implementation of an anthropogenic project, environmental quality evaluation after a anthropogenic project is put into practice, environmental quality assessing after the decommissioning of an anthropogenic project, environmental quality assessment after the rehabilitation of the area of interest and to evaluate the environment at a time and identify and quantify of pollution sources (in an area of interest) and evaluating environmental quality in crisis situations (earthquakes, landslides, hurricanes, tornadoes, cyclones, drought, etc.). [2]

The necessity for weighting the reliability marks

One of the disadvantages of the method is that

the establishment of the reliability marks for environmental factors, as a method of calculating, is considered the arithmetic mean of the reliability marks awarded for each quality parameter describing the environmental factor in question. In other words it is considered that each parameter involved in determining the final reliability mark in terms of importance is equally.

Looking at this procedure, especially in terms of the relationship between quality parameters of the environmental factors (water) and human health is easy to understand why it is considered a disadvantage of the method. It is clear that in terms of action of pollutants on human health, of flora and fauna, of their toxicity, the possibility that a pollutant is present in an environmental compartment at a concentration considered to be dangerous to the health, of flow regime and the possibilities for self-cleaning, are different and for these grounds requires a weighting of reliability marks, in view of those above.

Below is presented a way of achieving this weighting factor for water (surface water), mentioning that for establishing the weighting factors an urban area typology was especially considered. Identifying the weighting factors for surface water quality parameter

Weighting factors assigned values (taking into account the criteria outlined above) are presented in Tables 1, 2 and 3.

Radioactivity on the existing rules establish the following benchmarks: for drinking water maximum annual effective dose 0,1 mSv/year, 0,1 Bq/dm3 alpha activity, beta activity Bq/dm3 1,0, and for beta activity of natural waters three benchmark 2,0 Bq/dm3 - threshold of attention, 5,0 Bq/dm3 - warning threshold, 20,0 Bq/dm3 - alarm threshold. Whatever type of water (fresh, flowing, natural lake or reservoir) the weighting factor assigned is 10.

Table 1. Indicators for the eutrophication process

Category of natural lake or reservoir (MAC in conformity with Order 1146/2002) Crt.

no. Parameter Measuring unit (MU)

Ultraoligotrophic

Oligotrophic Mesotrophic Eutrophic Hypertrophic

1 Nutrients

P total /N mineral total

mg/dm3/mg/dm3

0,005/0,200 0,005-

0,01/0,2-0,4

0,01-0,03/0,4-

0,65

0,03-0,1/0,65-

1,5 >0,1/1,5

2 Biomass of phytoplankton mg/dm3 0 - 1 1 - 3 3 - 5 5 - 10 over 10

3 Chlorophyll „a”

mg/dm3 (annual

average/maximum annual average)

<1/<2,5 <2,5/<8 2,5-8/8-25 8-25/25-75 27-75/>75

4 Dissolved

oxygen saturation

% over 70 over 70 10 - 70 under 10 under 10

12


It is believed that all indicating parameters of the degree of eutrophication have the same weighting factors and then the final reliability mark is calculate by the arithmetic average of the reliability marks awarded for each parameter, namely:

4,1; == ∑ iiNB

NB if ;

Where: NBf - the final reliability mark, NBi - the reliability mark given for each parameter.

Table 2. Sediments (fraction <63 μm)

Crt. no.. Parameter MU MAC cf. Ord. 1146/2002

Weighting factors (regardless of the flow regime or type of

lake) 1 Arsenic mg/kg 17 72 Cadmium mg/kg 3,5 83 Chromium mg/kg 90 64 Copper mg/kg 200 55 Lead mg/kg 90 66 Mercury mg/kg 0,5 107 Zinc mg/kg 300 38 Benz(a)pyren mg/kg 750 29 Lindane mg/kg 1,4 8

10 PCB - s mg/kg 280 4PCB – Polychlorinated biphenyls Reliability mark calculation:

( )∑

∑ ⋅=

i

iiF f

fNBNB

Where: NBf - final reliability mark, NBi -

reliability mark given for each parameter, fi - the weighting factor of each parameter.

For physical-chemical indicators (Table 3)

calculating the final reliability mark involves two stages: I. Calculate the reliability mark for each group of indicators of water quality parameters as:

( )∑

∑ ⋅=

i

iiG f

fNBNB

Where: NBG - reliability mark determined for

each group of indicators, NBi - reliability mark given for each parameter, fi - the weighting factor of each parameter.

II. The final reliability mark for the environmental factor of water is carried by the formula:

( )∑

∑ ⋅=

G

GGF f

fNBNB

Where: NBF - the final reliability mark for

environmental factor of water, NBG - reliability mark determined for each group of parameters separately, fG - weighting factor of each group.

For determining the weighting factors were taken into account the effects of each pollutant (or group of pollutants) on aquatic ecosystems (flora and fauna regardless of their place in the food chain), the possibilities of water use (especially for drinking water, for food and other sensitive uses that require strict quality conditions) and the toxicological data (direct and indirect influence on human health).

When for determining water quality analysis are performed on the parameters contained in one group then the final reliability mark for water will be equal to the mark of reliability obtained for group in question.

If only one parameter is determined from a group, then its assigned weighting factor is equal to the weighting factor of the respective group.

Weighting factors have values between 1 and 10 (1 a very low importance and 10 the utmost importance).

13


Ta

ble

3. P

hysi

co-c

hem

ical

indi

cato

rs fo

r sur

face

wat

er q

ualit

y M

AC

Cat

egor

y of

qua

lity

cf. O

rd. 1

146/

2002

U

sed

wat

ers c

f. G

D

352/

2005

C

rt.

no.

Gro

up

Para

met

er

MU

I II

II

I IV

V

N

TPA

00

1 N

TPA

00

2

Wei

ghtin

g fa

ctor

(tu

rbul

ent

flow

re

gim

e)

Wei

ghtin

g fa

ctor

(la

min

ar

flow

re

gim

e an

d la

kes)

Gro

up

wei

ghtin

g fa

ctor

1 Te

mpe

ratu

re

ºC

nn

nn

nn

nn

nn

35

40

3 5

2 pH

pH

uni

ts

6,5-

8,5

6,5-

8,5

(9)

6,5-

8,5

6 6

3

Phys

ical

in

dica

tors

Su

spen

sion

s m

g/dm

3 nn

nn

nn

nn

nn

35

(60)

35

0 3

3

4

4 D

O

mgO

2/dm

3 7

6 5

4 <4

nn

nn

8

9 5

BC

O5

mgO

2/dm

3 3

5 10

25

>2

5 25

30

0 6

8 6

CC

O -

Mn

mgO

2/dm

3 5

10

20

50

>50

nn

nn

6 8

7

Oxy

gen

regi

me

CC

O -

Cr

mgO

2/dm

3 10

25

50

12

5 >1

25

125

500

6 8

8

8 N

H4-

mg/

dm3

<0,2

0,

2 0,

3 0,

6 >1

,5

2 (3

) 30

6

8 9

NO

2- m

g/dm

3 0,

01

0,06

0,

12

0,3

>0,3

1

(2)

nn

9 9

10

NO

3- m

g/dm

3 1

3 6

15

>15

25 (3

7)

nn

4 6

11

N to

tal

mg/

dm3

1,5

4 8

20

>20

10 (1

5)

nn

4 6

12

PO4-3

m

g/dm

3 0,

05

0,1

0,2

0,5

>0,5

nn

nn

7

8 13

P

tota

l m

g/dm

3 0,

1 0,

2 0,

4 1

>1

1 (2

) 5

6 8

14

Nut

rient

s

Chl

orop

hill

„a”

mg/

dm3

0,02

5 0,

05

0,1

0,25

>0

,25

nn

nn

7 8

6

15

Res

idue

filtr

ed a

t 10

5ºC

m

g/dm

3 bk

g 50

0 10

00

1300

>1

300

2000

nn

6

6

16

Na+

mg/

dm3

bkg

50

100

200

>300

nn

nn

4

5 17

C

a+2

mg/

dm3

75

150

200

300

>300

30

0 nn

3

4 18

M

g+2

mg/

dm3

bkg

25

50

100

>100

10

0 nn

3

4 19

Fe

tota

l m

g/dm

3 bk

g 0,

1 0,

3 1

>1

5 nn

5

7 20

M

n to

tal

mg/

dm3

bkg

0,05

0,

1 0,

3 >0

,3

1 2

6 7

21

Cl- (c

hlor

ides

) m

g/dm

3 bk

g 10

0 25

0 30

0 >3

00

500

nn

5 6

22

Gen

eral

ions

, sa

linity

SO4-2

m

g/dm

3 80

15

0 25

0 30

0 >3

00

600

600

4 5

5

23

Zn+2

μg

/dm

3 bk

g 5

10

25

>25

nn

nn

4 5

24

Cu+2

μg

/dm

3 bk

g 2

4 8

>8

nn

nn

6 6

25

Cr t

otal

μg

/dm

3 bk

g 2

4 10

>1

0 nn

nn

6

6 26

Pb

+2

μg/d

m3

bkg

1 2

5 >5

nn

nn

5

6 27

C

d+2

μg/d

m3

bkg

0,1

0,2

0,5

>0,5

nn

nn

8

9 28

H

g+2

μg/d

m3

bkg

0,1

0,15

0,

3 >0

,3

nn

nn

9 9

29

Ni+2

μg

/dm

3 bk

g 1

2 5

>5

nn

nn

4 5

30

Met

als

Dissolved fraction

As

μg/d

m3

bkg

1 2

5 >5

nn

nn

5

6

7

14


Con

tinua

tion

31

Zn+2

μg

/dm

3 bk

g 10

0 20

0 50

0 >5

00

500

1000

4

6 32

C

u+2

μg/d

m3

bkg

20

40

100

>100

10

0 20

0 5

6 33

C

r tot

al

μg/d

m3

bkg

50

100

250

>250

10

00

1500

5

6 34

Pb

+2

μg/d

m3

bkg

5 10

25

>2

5 20

0 50

0 6

7 35

C

d+2

μg/d

m3

bkg

1 2

5 >5

20

0 30

0 7

8 36

H

g+2

μg/d

m3

bkg

0,1

0,2

0,5

>0,5

50

nn

8

9 37

N

i+2

μg/d

m3

bkg

50

100

250

>250

50

0 10

00

5 6

38

Met

als

Total concentration A

s μg

/dm

3 bk

g 5

10

25

>25

100

nn

6 7

8

39

Phen

ols

μg/d

m3

fond

1

20

50

250

300

3000

0 7

8 40

D

eter

gent

s μg

/dm

3 fo

nd

500

750

1000

>1

000

500

2500

0 5

7 41

A

OX

μg

/dm

3 10

50

10

0 25

0 >2

50

nn

nn

6 8

42

Petro

leum

H

ydro

carb

ons

μg/d

m3

bkg

100

200

500

>500

50

00

nn

6 8

43

Lind

ane

μg/d

m3

0,05

0,

1 0,

2 0,

5 >0

,5

nn

nn

9 9

44

DD

T μg

/dm

3 0,

001

0,01

0,

02

0,05

>0

,05

nn

nn

10

10

45

Atra

zine

μg

/dm

3 0,

02

0,1

0,2

0,05

>0

,05

nn

nn

9 9

46

Tric

lorm

etha

ne

μg/d

m3

0,02

0,

6 1,

2 1,

8 >1

,8

nn

nn

9 9

47

Tetra

clor

met

hane

μg

/dm

3 0,

02

1 2

5 >5

nn

nn

8

9 48

Tr

ichl

oret

hane

μg

/dm

3 0,

02

1 2

5 >5

nn

nn

8

9 49

Org

anic

su

bsta

nces

Tetra

chlo

reth

ane

μg/d

m3

0,02

1

2 5

>5

nn

nn

8 9

10

50

Sapr

odic

inde

x M

ZB

<1

,8

1,81

-2,

3 2,

31-

2,7

2,71

-3,

2 >3

,2

nn

nn

5 6

51

Tota

l col

iform

s co

loni

es/1

00m

l 50

0 10

000

nn

nn

nn

nn

nn

6 6

52

Bio

logi

cal a

nd

mic

robi

olog

ical

in

dica

tors

Fe

cal c

olifo

rms

colo

nies

/100

ml

100

2000

nn

nn

nn

nn

nn

8

10

8

53

CN

μg

/dm

3 nn

nn

nn

nn

nn

10

0 10

00

8 10

54

S-2

, HS-

μg/d

m3

nn

nn

nn

nn

nn

500

1000

6

8 55

SO

3-2

μg/d

m3

nn

nn

nn

nn

nn

1100

20

00

7 8

56

Cl 2

(res

idua

l) μg

/dm

3 nn

nn

nn

nn

nn

20

0 50

0 4

6 57

C

r+6

μg/d

m3

nn

nn

nn

nn

nn

100

200

6 7

58

Co+2

μg

/dm

3 nn

nn

nn

nn

nn

10

00

nn

5 6

59

Se+2

μg

/dm

3 nn

nn

nn

nn

nn

10

0 nn

6

7 60

M

o+2

μg/d

m3

nn

nn

nn

nn

nn

100

nn

6 7

61

Ag+2

μg

/dm

3 nn

nn

nn

nn

nn

10

0 nn

5

6 62

Oth

er

indi

cato

rs

Al+3

μg

/dm

3 nn

nn

nn

nn

nn

50

00

nn

5 7

7

() –

val

id v

alue

s for

Dan

ube

river

, nn

– no

t - n

orm

ed, D

O –

dis

solv

ed o

xyge

n, A

OX

– o

rgan

ochl

orin

e su

bsta

nces

, bkg

– b

ackg

roun

d.

15


Example to highlight the importance of study

To show how the reliability mark is influenced for the environmental factor water when the weighting factors are applied to calculation was considered following example (data from Table 4 represents a real case): Table 4. Water quality analysis

Crt. no. Parameter MU

Average determined

values RM

1 pH unit pH 6,71 10 2 Diss. O2 mg/dm3 8,61 8 3 NH4

+ mg/dm3 0,34 9 4 NO2

- mg/dm3 0,04 7 5 HS- mg/dm3 0,02 9 6 Fe mg/dm3 0,11 9 7 CCO-Mn mg/dm3 38,14 4 8 Cl- mg/dm3 14,29 9 9 Ca mg/dm3 25,83 9

10 Mg mg/dm3 6,03 9

If we calculate the reliability mark for this case based on the arithmetic average a 8,3 value is achieved.

If we apply the methodology of calculation of the reliability mark presented, by using weighting factors, for turbulent flow regime is obtained a value of 8,17 and for laminar flow regime and lakes a value of 8,03 is obtained. Conclusions

The decrease of the reliability mark for groups in which several parameters were analyzed leads to a sensitive decrease in the final reliability mark. So we can say that to characterize water quality based on the importance of the analyzed parameters

requires more complex analysis, to determine the concentration of as many elements and substances present in water.

Although the decrease of the reliability mark is of only 0,13 respectively 0,27 if we would analyze more parameters the decrease could be a much more significant, and if we apply similar methodologies for the other environmental factors (soil, air, flora and fauna, landscape), and taking into account the method of calculation of the global pollution index (ratio of surface area of the ideal state and surface area of actual state - which in this case would decrease), its value could be changed significantly (for instance from a value between 1 and 2 - environment affected by human activities within reasonable limits to a value between 2 and 3 - environment affected by human activities causing discomfort for life forms).

This method can also be seen as one of finesse, being able to identify in detail those very values of global pollution index located at the boundary between two categories of environment (as they were defined conventionally) References: 1. Dumitrescu, I., Lazăr, M. Human Impact on the Environment (in romanian), Universitas Publishing House, Petrosani, 2006. 2. Florea Ad. Environmental Monitoring (in romanian), Petrosani, course support, 2005. 3. *** Order 1146/2002 of 10.12.2002 published in Official Gazette no. 197 of 27.03.2003. 4. *** GD 352/2005 of 21.04.2005, published in Official Gazette no. 398 din 11.05.2005.

16


DETERMINATION OF POSSIBILITIES OF THE ACTIVE LATERAL EARTH PRESSURE ON ABUTMENT WALLS OF ENLARGED ROADWAYS

Carmen Georgeta FLOREA*, Adrian Alexandru DRESCHER*, Vlad Alexandru FLOREA*

Roads are often the object of modernisation works, especially widening works. Therefore, where the slope needs reinforcements, the determination of a redesign of abutment walls is compulsory.

Keywords: reinforcement, slope, abutment wall, lateral active pressure. Introduction

Slope reinforcement works of roadways imply

the design of works in order to support them. The common practice is to stabilise the slope

with backfill or embankment concrete wall comprising the following operations: 1. Creating the charging platform; 2. Digging and supporting the embankment; 3. Foundation execution; 4. Elevation execution; 5. Back drainage execution; The concrete reinforcement works for the construction of backfilling and embankment walls need to be correlated both with the necessities required by the improvement of geometric elements of the trajectory as well as with the need of eliminating the danger from unstable slope areas and are executed where the centre of the designed road has moved either towards the surety or the slope and no other reinforcement works can be made. Therefore, the area is geotechnically analysed, highlighting the nature of the terrain. The paper analyses the possibility to design and execution of reinforcement works for the support of a right slope of a national road in Hunedoara County the roadway of which needs to be widened. The high eclecticism of the material in the area, namely rock fragments in sandy mass, makes the establishment of resistance characteristics difficult through laboratory trials on unaffected samples, and with a representative characteristic of results. It is difficult to collect samples from such an unaffected material, and in the same time to ensure a corresponding scale factor in order to be able to model the load behaviour of the clay-bearing sandy rock fragments, (the dimension of the usual samples are comparable to rock fragments). ____________________________________ * University of Petroşani

The geotechnical resistance characteristics of these materials (dusty sand mixed with cement and sandy clay comprising rock fragments) are mainly given by fine cohesive earth in their composition, being the ones to give their geological behaviour to water. Therefore, the design solution was made starting from the resistance characteristics of the soil which had been indirectly established through parametric determinations, considering at first the physical characteristics of the material and STAS 3300/1-85 recommendations.

Considering, both the nature and configuration of the terrain, with slopes of approximately 40°, the stability and conditions for ensuring it necessary for excavations required by the concrete abutment wall, were imposed.

The determination of the stability to sliding has been made using the Bishop method.

Verifying the stability to sliding implied as well the determination of resistance characteristics of the soil and establishing them by a parametric determination. The static and pseudostatic determination was made for the seismic acceleration a = 0.08g, (the configuration of the ground being that preceding the execution of reinforcement works), the purpose of which is to verify the resistance characteristics of the ground and establishing them using a parametric determination.

The determination was made for the profile presented in figure 1 considering an unfavourable configuration of the ground. The minimum value of this basic characteristic of the ground – cohesion – considering the limit assurance of sliding stability, resulted in this step:

c = 35 kPa Classifying the soil in the studied area as soft

rocks characterised by resistance parameters mentioned above, implies the use of backfill slopes as it is mentioned in the speciality literature, of a 1:1 ratio for slopes of 5.0m. Due to terrain configuration, the excavation necessary for the abutment wall requires in its turn extra-excavation towards he peak of the slope. Adopting the solution using backfill slopes depends on their required geometry; a total volume of extra-excavation of approximately 450 m3/ml with 3.0m berms between the backfillings. Adopting a backfill slope of 2:1, and considering the temporary characteristic of the excavation, the total volume would reduce to

17


approximately 300 m3/ml. Another thing remaining to be done, besides these excavation volumes, is the wall emplacement. These excavations reach somewhere around 10m while their supports in order to maintain traffic conditions in the area, represent a great problem.

Therefore, the method of the wall on a certain segment will be completed with a support method made with anchored plates (for areas with large heights, over 4.0m). This kind of solution reduces the volume of the excavation to approximately 26 m3/ml and facilitates the execution, on steps, downward, with no important implications on ensuring the requirements of the traffic. Designing an abutment wall

Geotechnically speaking, on the studied place, an abutment wall in reinforced concrete will be designed (Figure 1) which will meet the resistance and stability for such civil construction elements. The steps taken for the determinations are the following: 1. Determining the active pressure (in Coulomb’s hypothesis); 2. The determination of the resultants of the active pressures acting on the wall; 3. Checking the abutment wall for:

a) Stability to tilting; b) Stability to sliding; c) Pressures on the bearing surface of the

foundation of the wall. 4. Determining the reinforcement of the abutment.

Form characteristics of the abutment wall correspond to those presented in Figure 1.

Figure 1 Abutment wall profile

H – Elevation height – 5.2 m D – Foundation height – 1.0 m

Determining the coefficients of active lateral earth pressure ( ka )

ka coefficients are used for the determination of

earth’s pressure on the element of construction, considering the layers of the material placed behind the abutment wall.

The design of the wall is made on the layers of the drilling considering its inclination at an angle β = 3°.

2

2

2

sin ( )

sin( ) sin( )sin sin( ) 1sin( ) sin( )

ak q j

j d j bq q dq d q b

+= é ůć ö+ × -ę úç ÷× - × +ę úç ÷- × +ę úč řë ű where: φ – is the internal friction angle of the ground

θ – the inclination angle of the bearing surface of the foundation

δ – the inclination angle of the lateral earth pressure

Replacing them in relation (1) the values of the coefficient of pressure will be obtained: For layer S1 (Figure 2) :

h1 = 1.70 m ; where h1 is the height of layer 1

θ1 = 90°; φ1 = 17.60º;

δ1 = 13

φ1 = 13

·17.60º = 5.87º

β = 3° 2

1 2

2

sin (90 17.6 ) 0.5259sin(17.6 5.87 ) sin(17.6 3 )sin 90 sin(90 5.87 ) 1

sin(90 5.87 ) sin(90 3 )

ο ο

ο ο ο οο ο ο

ο ο ο ο

+= =

⎡ ⎤⎛ ⎞+ ⋅ −⎢ ⎥⎜ ⎟⋅ − ⋅ +⎜ ⎟⎢ ⎥− ⋅ +⎝ ⎠⎣ ⎦

ak

for layer S2 (Figure 2): h2 = 2.00 m ;

where h2 is the height of layer 2 θ2 = 90°; φ2 = 18.20º;

δ2 = 13

φ2 = 13

·18.20º = 6.07º

β = 3° 2

2 2

2


sin(90 6.07 ) sin(90 3 )

ο ο

ο ο ο οο ο ο

ο ο ο ο

+= =

⎡ ⎤⎛ ⎞+ ⋅ −⎢ ⎥⎜ ⎟⋅ − ⋅ +⎜ ⎟⎢ ⎥− ⋅ +⎝ ⎠⎣ ⎦

ak

for layer S3 (Figure 2) h3 = 1.50 m;

where h2 is the height of layer 2 θ3 = 90°; φ3 = 20.20º;

δ3 = 13

φ3 = 13

·20.20º = 6.73º

β = 3° 2

a3 2

2

sin (90 20.2 )k 0.4743sin(20.2 6.73 ) sin(20.2 3 )sin 90 sin(90 6.73 ) 1

sin(90 6.73 ) sin(90 3 )

ο ο

ο ο ο οο ο ο

ο ο ο ο

+= =

⎡ ⎤⎛ ⎞+ ⋅ −⎢ ⎥⎜ ⎟⋅ − ⋅ +⎜ ⎟⎢ ⎥− ⋅ +⎝ ⎠⎣ ⎦

for layer S´3 (Figure 2)

18


h´3 = 0.306 m;

where h´3 is the height of layer 3´

θ´3 = 85°;

φ´3 = 20.20º;

δ´3 = 1

3 φ´

3 = 13

·20.20º = 6.73º

β = 3° 2

3 2

2


sin(85 6.73 ) sin(85 3 )

ο ο

ο ο ο οο ο ο

ο ο ο ο

+′ = =⎡ ⎤⎛ ⎞+ ⋅ −⎢ ⎥⎜ ⎟⋅ − ⋅ +⎜ ⎟⎢ ⎥− ⋅ +⎝ ⎠⎣ ⎦

ak

for layer S´´3 ( Figure 2 ) h´´

3 = 0,194 m ; where h´´

3 is the height of layer 3´´ θ´´

3 = 90°; φ´´

3 = 20.20º;

δ´´3 = 1

3 φ´´

3 = 13

·20.20º = 6.73º

β = 3° 2

3 2

2


sin(90 6.73 ) sin(90 3 )

ο ο

ο ο ο οο ο ο

ο ο ο ο

+′′ = =⎡ ⎤⎛ ⎞+ ⋅ −⎢ ⎥⎜ ⎟⋅ − ⋅ +⎜ ⎟⎢ ⎥− ⋅ +⎝ ⎠⎣ ⎦

ak

Figure 2 Layer of materials acting on the abutment

wall (AB, BC, CD, DE, EF) Establishing the distribution of the active lateral earth pressure

The determination of the active lateral earth pressure resultants acting on the abutment wall

Establishing the active pressures (pa), as well as the total active lateral push, (Pa) is made analytically. a) Establishing the distribution of the active pressure

sincosa ap h k qg

d= × × ×

For layer S1 (Figure 3): 1 1

1 0 11

sin 0cosaA ap h k qg

d= × × × =

1 211 1 1

1

sin sin9020.79 1.7 0.5259 18.68 /cos cos5.87

θγδ

= ⋅ ⋅ ⋅ = ⋅ ⋅ ⋅ =aB ap h k kN m


2 1 22

sin sin9020.77 1.71 0.5135 18.34 /cos cos6.07

θγδ

= ⋅ ⋅ ⋅ = ⋅ ⋅ ⋅ =aB e ap h k kN m

1 1 21

2 2

sin 20.79 1.7 sin 90 1.71sin( ) 20.77 sin(90 3 )

γ θγ θ β⋅ ⋅

= ⋅ = ⋅ =+ +e

hh m

2 22 1 2 2

2

2

sin( )cos

sin 9020.77 (1.71 2) 0.5135 39.79 /cos 6.07

θγδ

= ⋅ + ⋅ ⋅

= ⋅ + ⋅ ⋅ =

aC e ap h h k

kN m


3 2 33

2

sincos

sin9020 3,85 0,4743 36,78 /cos6,73

aC e ap h k

kN m

qgd

= × × × =

× × × =

31 1 2 22

3 3

sinsin( )

20.79 1.7 20.77 2 sin 90 3.8520 sin(90 3 )

θγ γγ θ β

⋅ + ⋅= ⋅ =

+

⋅ + ⋅⋅ =

+

eh hh

m

3 33 2 3 3

3

2

sin( )cos

sin 9020 (3.85 1.5) 0.4734 48.23 /cos6.73

θγδ

= ⋅ + ⋅ ⋅ =

⋅ + ⋅ ⋅ =

aD e ap h h k

kN m

For layer S´3 (Figure 3): 3 3

3 2 33

2

sincos

sin9020 5.35 0.5107 55.02 /cos6.73

θγδ′

′ ′ ′= ⋅ ⋅ ⋅ =′

⋅ ⋅ ⋅ =

aD e ap h k

kN m

1 1 2 2 3 3 32

3 3

sinsin( )

20.79 1.7 20.77 2 20 1.5 sin90 5.3520 sin(90 3 )

γ γ γ θγ θ β

′⋅ + ⋅ + ⋅′ = ⋅ =′ ′ +

⋅ + ⋅ + ⋅⋅ =

+

eh h hh

m

3 33 2 3 3

3

2

sin( )cos

sin9020 (5.35 0.306) 0.5107 91.12 /cos6.73

θγδ′

′ ′ ′ ′= ⋅ + ⋅ ⋅ =′

⋅ + ⋅ ⋅ =

aE e ap h h k

kN m

For layer S´´3 (Figure 3): 3 3

3 2 33

2

sincos

sin9020 5.66 0.4743 54.06 /cos6.73

θγδ′′

′′ ′′ ′′= ⋅ ⋅ ⋅ =′′

⋅ ⋅ ⋅ =

aE e ap h k

kN m

1 1 2 2 3 3 3 3 32

3 3

sinsin( )

20.79 1.7 20.77 2 20 1.5 20 0.306 sin 90 5.6620 sin(90 3 )

γ γ γ γ θγ θ β

′ ′ ′′⋅ + ⋅ + ⋅ + ⋅′′ = ⋅ =′′+

⋅ + ⋅ + ⋅ + ⋅⋅ =

+

eh h h hh

m

3 33 2 3 3

3

2

sin( )cos

sin9020 (5.66 0.194) 0.4743 55.92 /cos6.73

θγδ′′

′′ ′′ ′′ ′′= ⋅ + ⋅ ⋅ =′′

⋅ + ⋅ ⋅ =

aF e ap h h k

kN m

19


Figure 3 Distribution of lateral pressures

b) Active pressure resultants determination for layer S1 (Figure 3):

2 21 1 1 1

1 1 20.79 1.7 0.5259 15.8 /2 2γ= ⋅ ⋅ ⋅ = ⋅ ⋅ ⋅ =a aP h k kN m


2 2 2 22

2

1 2(1 )2

1 2 1.7120 2 0.5135 (1 ) 57.81 /2 2

γ ⋅= ⋅ ⋅ ⋅ ⋅ + =

⋅⋅ ⋅ ⋅ ⋅ + =

ea a

hP h kh

kN m


3 3 3 33

2

1 2(1 )2

1 2 3.8520 1.5 0.4743 (1 ) 65.45 /2 1.5

γ ⋅= ⋅ ⋅ ⋅ ⋅ + =

⋅⋅ ⋅ ⋅ ⋅ + =

ea a

hP h kh

kN m

2 2 20,2(45 ) (45 ) 0.4872 2ϕ

= ⋅ − = ⋅ − =Fk tg tg

2 23

1 1 0.487 20 1 4.87 /2 2

γ= ⋅ ⋅ ⋅ = ⋅ ⋅ ⋅ =F F fP k D kN m

For layer S´3 (Figure 3): 2 2

3 3 3 33

2

1 2(1 )2

1 2 5.3520 0.306 0.5107 (1 ) 254.72 /2 0.306

γ′⋅′ ′ ′ ′= ⋅ ⋅ ⋅ ⋅ + =′

⋅⋅ ⋅ ⋅ ⋅ + =

ea a

hP h kh

kN m

For layer S´´3 (Figure 3): 2 2

3 3 3 33

2

1 2(1 )2

1 2 5.6620 0.194 0.4743 (1 ) 10.59 /2 0.194

γ′′⋅′′ ′′ ′′ ′′= ⋅ ⋅ ⋅ ⋅ + =′′

⋅⋅ ⋅ ⋅ ⋅ + =

ea a

hP h kh

kN m

c) Vertical and horizontal active pressure protections

1 1 1cos( ) 15.8 cos(3 5.87 ) 15.61 /β δ= ⋅ + = ⋅ + =Ha aP P kN m

1 1 1sin( ) 15.8 sin(3 5.87 ) 2.44 /β δ= ⋅ + = ⋅ + =Va aP P kN m

2 2 2cos( ) 57.81 cos(3 6.07 ) 57.09 /β δ= ⋅ + = ⋅ + =Ha aP P kN m

2 2 2sin( ) 57.81 sin(3 6.07 ) 9.11 /β δ= ⋅ + = ⋅ + =Va aP P kN m 3 3 3cos( ) 65.45 cos(3 6.73 ) 64.51 /β δ= ⋅ + = ⋅ + =H

a aP P kN m 3 3 3sin( ) 65.45 sin(3 6.73 ) 11.06 /β δ= ⋅ + = ⋅ + =V

a aP P kN m 3 3 3cos( ) 254.72 cos(3 6.73 ) 251.06 /β δ′ ′ ′= ⋅ + = ⋅ + =H

a aP P kN m

3 3 3sin( ) 254.72 sin(3 6.73 ) 43.05 /β δ′ ′ ′= ⋅ + = ⋅ + =Va aP P kN m

3 3 3cos( ) 10.59 cos(3 6.73 ) 10.44 /β δ′′ ′′ ′′= ⋅ + = ⋅ + =Ha aP P kN m

3 3 3sin( ) 10.59 sin(3 6.73 ) 1.79 /β δ′′ ′′ ′′= ⋅ + = ⋅ + =Va aP P kN m

3cos( ) 4.87 cos(0 6.73 ) 4.83 /β δ= ⋅ + = ⋅ + =HF FP P kN m

3sin( ) 4.87 sin(0 6.73 ) 0.57 /β δ= ⋅ + = ⋅ + =VF FP P kN m

Analytic examination of the abutment wall

The analytic examination of the abutment wall consists in the examination to tilting and sliding of the wall.

The determination of the weights of the abutment wall considering that γconcrete = 24.50 kN/m3 and it is made for a length of 1m.

Figure 4 Determining the centre of gravity

of the terrain

1 1 1 0.5 5.2 1 24.5 63.7γ= ⋅ ⋅ = ⋅ ⋅ ⋅ =bG A kN 2 2 1 0.5 1 1 24.5 12.25γ= ⋅ ⋅ = ⋅ ⋅ ⋅ =bG A kN

3 3 1 0.194 3.5 1 24.5 16.64γ= ⋅ ⋅ = ⋅ ⋅ ⋅ =bG A kN

4 40.306 3.51 1 24.5 13.12

2γ ⋅

= ⋅ ⋅ = ⋅ ⋅ =bG A kN

1 0.5 0.5 1 20 5γ= ⋅ ⋅ = ⋅ ⋅ ⋅ =t tG A kN 1 1 1 0.18 3.5 1 20 12.84γ= ⋅ ⋅ = ⋅ ⋅ ⋅ =p pG A kN

2 2 1 1.7 3.5 1 20.79

2 3.5 1 20.77 1.5 1 3.5 20 374.09

γ= ⋅ ⋅ = ⋅ ⋅ ⋅ +

⋅ ⋅ ⋅ + ⋅ ⋅ ⋅ =p PG A

kN

3 3 1 0.5 0.306 3.5 1 20 10.71γ= ⋅ ⋅ = ⋅ ⋅ ⋅ ⋅ =p pG A kN Conclusions a) The examination to tilt of the abutment wall is being made through the determination of the mentioned proportion FSR of the stabilities and tilt to an inferior point of the foundation of the wall.

5 1 2 3 4

1 2 3 1 2 3

3 3

0.75 0.5 2.75 2.27 0.25

3.33 2.75 3.33 1 1 1

3.33 4.5 63.7 0.75 12.25 0.5 16.64 2.7513.12 2.27 5 0.25 12.84 3.33 374.09 2.75 10.71 3.332.44

= ⋅ + ⋅ + ⋅ + ⋅ + ⋅

+ ⋅ + ⋅ + ⋅ + ⋅ + ⋅ + ⋅

′′ ′′+ ⋅ + ⋅ = ⋅ + ⋅ + ⋅

+ ⋅ + ⋅ + ⋅ + ⋅ + ⋅+

tV V V

p p p a a a

V Va a

M G G G G G

G G G P P P

P P

9.11 11.06 43.05 3.33 1.79 4.5 1411.88+ + + ⋅ + ⋅ = kNm

1 2 3 3 34.07 2.67 1 0.298 0.065

0.67 15.61 4.07 57.09 2.67 64.51 1 251.06 0.29810.44 0.065 4.83 0.67 359.2

′ ′′= ⋅ + ⋅ + ⋅ + ⋅ + ⋅

+ ⋅ = ⋅ + ⋅ + ⋅ + ⋅+ ⋅ + ⋅ =

H H H H Hr a a a a a

HF

M P P P P P

PkNm

1411.88 3.93 1.5359.2

= = = ⟩stabSR

rast

MFM

It results therefore that the wall does not tilt under the action of the forces exerted by the earth.

20


b) the examination to sliding of the wall is made through the determination of the mentioned ration Fsl of the sum of the vertical forces FV as well as the horizontal ones FH (for sandy clay considering a coefficient f = (0.3 … 0.5) taken from STAS 3300/2-85, with the condition: Fsl ≥ (1.1 … 1.5)

1 2 3 3 31

15.61 57.09 64.51 51.06 10.44 4.83 203.54=

′ ′′= + + + + + =

+ + + + + =

∑Hn

H H H H H Hi a a a a a F

iF P P P P P P

kN

1 2 3 3 3 1 2 3 41

1 2 3 2.44 9.11 11.06 43.05 1.79 0.57

63.7 12.25 16.64 13.12 5 12.84 374.09 10.71 576.37

=

′ ′′= + + + + + + + + +

+ + + + = + + + + +

+ + + + + + + + =

∑Vn

V V V V V Vi a a a a a F

i

t p p p

F P P P P P P G G G G

G G G G

kN

1

1

576.37 0.5 1.41 1.1203.54

=

=

= ⋅ = ⋅ = ≥∑

∑

Vn

ii

sl nH

ii

FF f

F

The minimum value 1.1, imposed by coefficient Fsl is the bellow the result of the

determination, respectively 1,41, resulting therefore that the abutment wall is examined to sliding. References 1. C 56-85 Construction and installations works quality and commissioning norms 2. NE 012-99, partea A, aprobat de MLPAT cu ord. nr. 590N din 24.08.1999 Practice code, part A approved for the execution of MLPAT with concrete and reinforced concrete works 3. STAS 6657/2-89 Concrete and reinforced concrete prefabricated and pre-compressed. Quality check rules and methods 4. Costescu, I., Lucaci, Gh. Roads - Design Guide, Bucharest, 1993

21


TECHNICAL ASPECTS OF THE DISTRIBUTION JOINTS FROM E.M.C. JILŢ

Dumitru IACOB*

Abstract: If in recent decades the importance of power coal has diminished in some Western countries, in Romania this mineral resource has continued and will continue to play an important role both in the economic development of the country, as well as to provide a basis for citizens life. Substantial participation of coal to support the economic activity in Romania is mainly carried out by its use as the main source of electricity production. Keywords: distribution joints, lignite, flow sheet, belt conveyors.

Making an analysis of the current state of Romanian energy sector it is shown that the main objective is to improve the energy efficiency due to optimal use of primary energy resources (coal, natural gas, oil) to reduce energy dependency on other countries.

While reducing the oil and gas reserves, the role of indigenous coal and especially lignite has increased in the national energy balance.

Romania's lignite resources are estimated at 1.490 million tons, of which 445 million tones are exploited in the leased perimeters, and those located in other perimeters which are not leased, are about 1.045 million tons, located in Oltenia mining basin.

Because of the growing role of lignite in electricity production it is impose the superior capitalization of these reserves by adopting regulations to ensure rational and total exploitation (lossless) under conditions of maximum efficiency both in terms of exploitation, transport and storage at the beneficiary.

Considering these aspects, the lignite exploitation activity in the mining perimeters from Jilt basin is strictly controlled to ensure the needs of coal power plant Turceni, taking into account the increasing efficiency throughout the resource-production-transport-consumption chain.

According to this, it has been established several main objectives of the development strategy:

adaptation of the technical potential of mining units to the demands for coal; ____________________________________ *Eng. – Turceni Energy Complex

carry out the upgrading and modernization programs;

adaptation of organizational structures to the requirements of production capacity levels. Distribution joints

The main tasks of the coal transport in the coal pits consist of moving the power coal to storage and delivery points, and from there to power plants, using the rail transport, respectively Drăgoteşti-Turceni on a distance of 38 km to the power plant scaffold.

The 'junction' is defined as the chosen place, outside the coal pit to which converge all the technology lines which transport the excavated mining mass from the coal pit and which ensure the distribution of tailings and coal to the storages.

For choosing the location, it has been considered the following criteria: - to have a period of activity for at least 12 years; - to ensure the connection of all excavation process lines to the main road which goes to the inner dumps and the coal storage; - the junction can be used without disruption of coal pit activity.

The factors which influence the choice of junction location are: - geometric shape of the exploitation perimeter; - the dump location; - the location of coal deposits; - landforms adjacent to the perimeter; - the existence of social and industrial buildings that need to be protected. Analyses of distribution joints subsystem

For the coal pits from Jilt mining basin, which

in the first half of 2011 have made more than 3,500 thousand tons of lignite, each coal pit has one distribution joint. Among the deficiencies noted in their operation: - aging and obsolescence, because the main circuits are very old (over 12 years old); - there haven't been upgrades for mechanical part or electrical part; - the structure of distribution joints can affect the coal pits acticvity because the serial belt circuits on transport flow, preparation and distribution;

22


- at the Jilț South coal pit, there is a decreasing in the junction efficiency, five belts goes in and three goes out for sterile, imposing the fourth output for sterile into the interior dump.

At present and in future (2025), the studies of increasing the extraction capacity lead to the need of increasing the transport capacity, storage, loading and delivery of Jilț North coal pit for not creating discrepancies in delivery of extracted lignite production.

To establish the narrow places, measures and actions to be taken to remove them, there is the necessity to optimize the technological flow at the household of Jilț North coal pit.

To remove the narrow places, the works to the Jilț North coal household has to be provided and the amplification of the lines device before the station, as well and a whole series of measures that will lead to better operation of existing plants and to avoid disruptions due to the equipment failure in the flow.

Under the existing technological flow resulting of a coal pit, results that the technological equipment components are connected in series, leading to failures or disruption if a component fail to work.

Diagnostic and statistical analysis shows us the main mechanical and electrical faults in the parts of the components located in the distribution joins.

These are: a) mechanical faults:

- destruction of barrel arbor; - seizure of the reducer balls of the driver gear; - weakening of fixing on the chassis of the driver gear; - low-reliability of some components which support the carpet rubber; - higher weight of the driver gear; - inefficient cleaning of the rubber carpet.

b) electrical faults: - rotor strength for starting the main functions with frequent failures; - CAM 6 kW contacts type have a higher rate of failure; - electrical cable penetrations; - faults in the main control panel and especially in the emergency cord system.

Obtaining the performance comparable with those of the countries with a tradition in power coal extraction from coal pits is possible by upgrading the present equipment and the technological lines.

Rehabilitation program of the Jilț mining basin having as an objecting the coal requirements for Turceni power plant, aimed mainly the Jilț South coal pit, the main coal provider of power plant, especially in terms of raising the standard of the electrical components of dynamic commutation.

By the rehabilitation - modernization of the conveyor belts is expected to improve the main operating parameters: - increased hourly and annual productivity; - time reduction for functional disruption planned for revisions and repairs and incidental parking.

Upgrading and rehabilitation action for Jilț North coal pit has been considered the modernization of one coal pit line and I + II dump line.

In the coal pit may find the following results: - intensive index increased 1.4% due to increased of hourly production capacity; - increasing evolution of extensively used index by 4.4%; - upward change of general index of use, 1.8%.

In terms achieving the upgrade action, the following specifications are necessary: - design and manufacturing documentation was Romanian; - the listed modernization are made by Romanian companies; - throughout the process of modernization, the local part represented over 60% of the works. Technical solutions for improving the activity of distribution joints

Coal from the excavation benches, transported on front bands is discharged on two-lane collector. The existence of distribution points, equipped with extensible strip ends, has the role to open the door to more efficient use of working time of machines, using, where appropriate, the transport availability of the downstream circuits,because the possibilities that exist, that any line front to use any line of landfill or coal. This distribution method is applied successfully to Jilț North and Jilț South coal pit. In the distribution joint of Jilţ South go in five bands with extensible end and go out four, from which three go to the outer dump and one to the coal storage. The flow sheet is shown in figure 1.

Into the distribution joint from Jilț North coal pit go in 3 conveyor belts, sterile-coal (T225, T224 and T241) and go out only one conveyor belt for coal TMC1 and 3 for sterile (TMS2, TMS3 and T240).

It is necessary to maintain three lanes of sterile having considering the distribution of mining mass to the interior and outside dump. This conveyor belt system was designed and chosen so as to ensure evacuation of extracted mining mass (coal and sterile).

In the current exploitation conditions and operation of Jilț North coal pit is calculated for production transport for the current year and in the future: 2020 ÷2025. The flow sheet is shown in figure 2.

23


Figure 1. Flow sheet of Jilţ South coal pit - S.C. C.E.T. S.A

Figure 2. Flow sheet of Jilţ North coal pit - S.C. C.E.T. S.A

24


Since the belt conveyor of distribution joints of the two coal pits are older than 12 years, it is necessary to modernize them both on the mechanical and electrical-side. Modernization and rehabilitation measures aimed: the driving gears, return stations and layout elements. From the diagnosis analyze the following actions are required:

a) Mechanical part Driving gear - assembling the cylinder; - assembling the deflection cylinder; - activation on cleaning belts; - assembling the battery of intensive rakes; - modifying the bracing system of the rubber rake; - greasing the cylinders; - assembling the driving gear with 1 MAN band and stopping it’s functions. Layout - replacing the band sections of B1400 mm width with B2000 mm sections - mounting the brackets for adjustment of upper roller; - sections with adjustable height of vertical sides in connecting areas with the drive and return stations - arrangement of special places for vulcanization equipped with folding side sections with tripod for mat; Return station - mounting the carcase ploughs at the returning drums - mounting the roller bed with impact brackets for increasing the reliability; - changing the fixing system of drilling iron rods with improved quality for a quick replacement. b) Electrical part - changing the control facility - resizing the electrical houses; - installation of capacitor banks for power factor improvement; - complete dispatch of conveyors.

For Jilț South coal pit it is necessary the fourth exit (band) for sterile to the internal dump.

Technical solutions for improving the maintenance of belt conveyors

The bibliography shows that the maximum slope that can be used by smooth rubber bands to carry depends on how material is transported and the angle of lateral rollers. Thus, the maximum angle which can be used for upward transportation is 16° - 18° when the material is coarse grained and can reach up to 20° - 22° when the material is small and lean side rollers is 36°. When the material is transported downward, must be

considered that the maximum angle diminishes to 14° - 16°.

To use conveyor belt at larger angles are used different solutions which can be divided into:

increasing the adhesion coefficient between transported material and rubber mat;

increasing the down force of the material; usage of tall transverse walls or chicanes; tube band etc.

These solutions allow the gradient increasing

up to 25° - 90°, but in conditions of reducing the transport capacity. They can not be used in coal pits because the sterile rocks, mainly clay, are having a very high bond to rubber mat, making difficult their cleaning.

Qualities of conveyor belt should not be worsened by sticking of the transported material on the "wet" surface of rubber mat, which can cause fouling / clogged up the rubber rollers, requiring special measures of protection depending on the material nature and the cleaning rate imposed. Therefore, belt conveyors will be also equipped with drum cleaners, intensive cleaning devices and plough type.

Step key for upper and lower carrying rolls of rubber mat from the conveyor belt will be chosen depending on the allowable load of rollers, so as the rubber mat arrow between two consecutive rolls should be checked and not to exceed 0.5% ÷1.5% at the higher branch and 2% ÷ 3% lower branch.

After determining the type of rubber mat construction, according to the limit of strength and connection type (hot vulcanization) the diameters driving drums, for back and drift are chosen, which are dependent on traction maximum force and the rubber mat thickness.

The electrical wiring for driving and automation ensure the functioning of the conveyor belts in the centralized system of the technological line that works with the possibility of local control when running repairs and revisions. Experience shows that any equipment is subject to restrictions of the downstream / upstream equipment, depending on its position. The belt conveyor being a link of the technological chain has a blocking system for the upstream and downstream equipments by the automation scheme of technological line.

For proper functioning of the conveyor belt, was intended to use a whole series of security systems, which serve to prevent accidents, to protect the mining mass transport, to command and control the transport unit as a whole.

The justification of these measures, the use of transducers to prevent accidents and limit the

25


effects of possible technical accidents, is required by: - the need to protect the conveyor belt; - many possibilities of producing damages; - partialism of human observer's surveillance.

These security systems can perform the following checks on the transport system / checks on the rubber mat: - tensions; - centered movement; - slides / slips; - security of longitudinal tearing.

In order to determine the necessary power to

belt conveyors from distribution joints, I propose to use the computer program for automatic computation. User card: • File image: AEM – BSV. • Algorithmic language: BASIC • Generalities: The program was design for

automatic computation of power, necessary to start a belt conveyor. By using this program it will be solved the demands required in the electromechanical field.

• Input data: The program user will fill in the following data:

Table 1 No Specification Variable

coding

Maximum variable

dimensioning

Measureunit

1 Name Alphanumeric 7 character - 2 Length Digital (complete) 3 character m 3 Width Digital 3 character mm

4 Vertical deviation

Digital (real) Positive or negative 6 character m

5 Discharge Digital (complete) 4 character m3/h

• Output data: after starting the program, the following data result:

Tabel 2

No Specification Variable coding

Maximum variable

dimensioning

Measureunit

1 Power Digital (one decimal place) 4 character kW

• Editing: presentation of the main characteristics

to identify the transporter and the estimated parameters will be as table form in the number of copies requested by the user.

Edited data: - name of belt conveyor; - lenght of belt conveyor, m; - width of rubber mat, mm; - vertical deviation, m; - transportation discharge, m3/h; - power of driving units, kW.

Note: - due to computation program, the transport speed, ( 1,5; 3; 4,5 and 6 m/s). - for a good function of program, the user must respect the dimensions and the order of input data. Conclusions

In this stage, Romanian economy is subject to

constraints created especially by the lack of capital investment and lack of working capital arising from financial blockage.

The consequences of these major constraints are felt in slow steps to continue the modernization and rehabilitation of the lignite mining industry, important sector of the economy which requires funds from the state budget as grants and capital expenditure.

To provide a clear image of effects of possible modernization and rehabilitation would be necessary to follow the evolution of usage indices of equipment and specific costs before and after rehabilitation for a minimum of one year. It must be emphasized the importance of tracking the effects of rehabilitation to assess more accurately the effectiveness of such action (rehabilitation - modernization) and to take relevant decisions on the points and moments when is necessary to act for extending them widely.

After the analysis which has been performed and presented has resulted that during 2011-2025 to deliver the planned production of lignite from Jilt basin was necessary to modernize the distribution joints for improving the efficiency of activity.

After implementing the rehabilitation programs and in condition of sale can achieve better results compared to the situation when working without upgraded equipment.

The results of modernization and rehabilitation actions of flow sheets from the coal pit have lead to: - reducing the number of interventions / supervision staff by 5-10%; - lower electricity costs, materials and spare parts by 5-15%.

Therefore we can say that the actions of rehabilitation and modernization of flow sheets of the two coal pits should continue with modernization measures of distribution joints, for smooth transport activities of sterile into the dumps and coal transport into the storage related to these.

26


References : 1. Borceanu, Gh., Petrescu,O. Noi direcţii de acţiune pentru modernizarea dotării tehnice existente, îmbunătăţirea tehnologiilor de lucru şi proiectări de noi utilaje destinate carierelor de lignit de mare capacitate din România, Revista Mine, Petrol şi Gaze, nr. 11/1989 2. Fodor, D., Rotunjanu, I. ş a . Tehnologii moderne de exploatare în carierele de lignit, Revista Mine, Petrol şi Gaze, nr.61/1979

3. Iacob, D. Deficienţe în sistemul de transport al carbunelui la beneficiar, Referat de doctorat nr. 2, Universitatea din Petroşani, 2010 4. Jula, D., Dumitrescu, I. Fiabilitatea sistemelor de transport, 2009 5. Nan, M.S., Jula, D. Capacitatea sistemelor de transport, Editura Universitas, Petroşani, 2000

27


SENSIBILITY ANALYSIS OF THE SUBSIDENCE PARAMETERS AT THE VARIATION OF THE MAIN GEO-MINING FACTORS

Dacian Paul MARIAN*, Ilie ONICA**, Eugen COZMA**

In this paper, there are presented the results of a complex analysis, with finite element method modelling, on the influence of the coal mining subsidence parameters at the variation of the following geo-mining factors: main geo-mechanical features; mining depth; coal seam dip; mining goaf sizes; horizontal stress; the presence of the near mining space. Keywords: coal seam, subsidence, horizontal displacement, finite element method, geo- mechanical characteristics, mining depth, horizontal stresses. Introduction

The underground mining of the coal deposits by roof rock caving leads to the massive stress and strain change and implicitly to the ground surface deformation, where a subsidence basin is formed. The main parameters of the subsidence basin are the subsidence and horizontal displacement [3], [5], [6], [10]. To analyse the behaviour manner of these

parameters at the variation of certain geo-mining factors, the 2D finite element modelling [4], [7], [8], [9] was used, with the aid of the CESAR-LCPC software [12]. In this effect, was achieved the homogenous numerical models and in the centre of these was executed the mining voids that simulate the extracted volume of the coal seam with longwall faces. In these models there were taken into consideration two zones of the massive with different characteristics, specifically for the rocks of the Jiu Valley coal basin [1], [11]: the first zone involves the surrounding rocks of the roof and floor of the coal seam and the second zone is attributed to the coal seam.

The rock characteristics, considered as homogenous and isotropic, taking into calculus the elasto – plastically without hardening behaviour hypothesis, are the following: apparent density; Young modulus of elasticity, E; Poisson ratio, ν ; compressive strength, cσ ; tensile strength, tσ ; cohesion , C; internal friction angle, ϕ (Tab. 1) [1], [11].

Table 1 Geo-mechanical characteristics values of the rocks of the two distinct areas of finite elements models

Rock characteristic Symbol UM Rocks Coal

Apparent density aρ kg/m3 2663 1450 Young modulus of elasticity E kN/m2 5 035 000 1 035 000

Poisson ratio ν - 0,19 0,13 Cohesion C kN/m2 6 130 1 300

Internal friction angle ϕ o 55 50

Sensibility analysis of the physical and mechanical characteristics

Apparent density influence In view to study the influence level of the apparent density of the rocks on the behaviour of finite element models, from the point of view of the main parameters of the subsidence, the average value of the rocks density will be multiplied by a coefficient K (K=1; 1.3; 1.5; 1.7; 2) [7], [9], keeping the other parameters constant (at the value presented in the ____________________________________ *Ph.D eng. University of Petroşani ** Prof.eng. Ph.D University of Petroşani

table 1). It’s mentioned that the same sensibility analysis could be achieved taken as parameter the apparent specific weight.

By consequence of the calculus made on these models it was found that the subsidence and horizontal displacement increase linearly at the same time with the apparent density increase (Fig.1), which demonstrates the pronounced sensitivity of the model at the rock density variation (and implicitly of the apparent specific weight) [2]:

5178.90585.0max −⋅= ρW , R2 = 0.9999 (1) 1921.40211.0max −⋅= ρU , R2 = 0.9998 (2)

3737.00166.0min +⋅−= ρU ,R2 = 0.9999 (3)

28


W max = 0,0585*ρ - 9,5178R2 = 0,9999

100

150

200

250

300

350

2500 3000 3500 4000 4500 5000 5500Apparent density - ρ (kg/m3)

Max

imum

sub

side

nce

- W

max

(mm

)

a)

U max = 0,0211*ρ - 4,1921R2 = 0,9998

U min = -0,0166*ρ + 0,3737R2 = 0,9999

-100

-50

0

50

100

150

2500 3000 3500 4000 4500 5000 5500

Apparent density - ρ (kg/m3)

Horiz

onta

l dis

plac

emen

t - U

(mm

)

b)

Fig.1. Apparent density influence on the: a) maximum subsidence;

b) maximum / minimum horizontal displacement

Elasticity modulus influence

The study of the rocks elasticity modulus influence [1], [11] on the development of the main subsidence parameters was made by reducing the value of this main parameter that characterises the elastically behaviour of rocks with a coefficient K (K=1; 0.7; 0.5; 0.3) [7], [9], keeping the other parameters unchanged, in conformity with the values from Table 1.

In analysis of the obtained results from the finite element models it was concluded that the subsidence and horizontal displacement increases significantly with the elasticity modulus decrease (Fig.2), which shows a very large impact of the elasticity modulus on the model behaviour. The variation of the main subsidence parameters depending on the rocks elasticity modulus is shown in the following relations [2]:

EW 110423.7 8

max ⋅⋅= , R2=1.0 (4)

EU 110639.2 8

max ⋅⋅= , R2=1.0 (5)

8.1357ln602.85min −⋅= EU ,R2=0.969 (6)

W max = 7,423*108*E -1,000

R2 = 1,000

0

100

200

300

400

500

600

0 1000000 2000000 3000000 4000000 5000000 6000000Elasticity modulus - E (kN/m2)

Max

imum

sub

side

nce

- W

max

(mm

)

a)

U max = 2,639*108*E -1

R2 = 1,000

U min = 85,602*ln(E ) - 1357,8R2 = 0,969

-200

-150

-100

-50

0

50

100

150

200

1000000 2000000 3000000 4000000 5000000 6000000

Elasticity modulus - E (kN/m2)

Horiz

onta

l dis

plac

emen

t - U

(mm

)

b)

Fig.2. Elasticity modulus influence on the: a) maximum subsidence;

b) max / min horizontal displacement

Poisson ratio influence

The model behaviour at the Poisson ration variation [1], [11] was obtained multiplying this parameter by a coefficient K (K=0.5; 1; 1.5; 2) and keeping the other parameters constant at the values shown in Table 1.

After analysis, it was concluded that the subsidence parameters (subsidence and displacement) have very little sensitivity at the Poisson ratio increase (Fig.3) [2]:

2,164368.91max +⋅−= νW , R2=0.999 (7)

15,55053.15max +⋅−= νU , R2=0.969 (8) 6,52316.48min −⋅= νU , R2=0.989 (9)

29


W max = -91,368*ν + 164,2R2 = 0,9997

125

130

135

140

145

150

155

160

0,000 0,050 0,100 0,150 0,200 0,250 0,300 0,350 0,400Poisson ratio - ν

Max

imum

sub

side

nce

- W

max

(mm

)

a)

Umax = -15,053*ν + 55,15R2 = 0,9939

Umin = 48,316*ν - 52,5R2 = 0,9896

-60

-40

-20

0

20

40

60

0,000 0,050 0,100 0,150 0,200 0,250 0,300 0,350 0,400

Poisson ratio - ν

Hor

izon

tal d

ispl

acem

ent -

U (m

m)

b)

Fig.3. Poisson ratio influence on the: a) maximum subsidence;

b) maximum / minimum horizontal displacement

Cohesion influence

To analyse the models subsidence behaviour in function of the rocks cohesion [1], [11] the cohesion will be multiplied by a coefficient K (K=0.5; 1; 1.5; 2) and keeping the other parameters constant.

After calculus on these finite element models, results that the subsidence and horizontal displacement decreases slowly with the cohesion increase (Fig.4). Therefore, it could be concluded that the variations of the cohesion influences the model very little, in conformity with the following correlations [2]:

0281.0max166.188

CW ⋅= ,R2=0.927 (10)

0328.0max106.70

CU ⋅= ,R2=0.911 (11)

W max = 188,66*C -0,0281

R2 = 0,9274

144

145

146

147

148

149

150

151

152

3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000Cohesion - C (kN/m2)

Max

imum

sub

side

nce

- W

max

(mm

)

a)

U max = 70,06*C -0,0326

R2 = 0,911

51

52

52

53

53

54

54

55

3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000Cohesion - C (kN/m2)

Horiz

onta

l dis

plac

emen

t - U

max

(mm

)

b)

Fig.4. Poisson ratio influence on the: a) maximum subsidence;

b) maximum horizontal displacement

Influence of the internal friction angle

The study of the behaviour of the subsidence and horizontal displacement of the ground surface in function of the variation of the rocks internal friction angle [1], [11] was made by successively reducing the internal friction angle by a coefficient K (K=1; 0.7; 0.5; 0.3), keeping the other parameters constant (Table 1).

After analysis, it was observed that the subsidence parameters decrease very little with increase of the internal friction angle (Fig.5), following the laws [2]:

0927.0max125.209

ϕ⋅=W , R2=0.8664 (12)

0897.0max1749.73

ϕ⋅=U , R2=0.8612 (13)

This leads to the conclusion that variations

of the internal friction angle influence the main subsidence parameters in little measure.

30


W max = 209,25*ϕ -0,0927

R2 = 0,8664

140

145

150

155

160

165

15 20 25 30 35 40 45 50 55Internal friction angle - ϕ (o)

Max

imum

sub

side

nce

- W

max

(mm

)

a)

U max = 73,749*ϕ -0,0897

R2 = 0,8612

51

52

53

54

55

56

57

58

59

15 20 25 30 35 40 45 50 55Internal friction angle - ϕ (ο)

Horiz

onta

l dis

plac

emen

t - U

max

(mm

)

b)

Fig.5. Internal friction angle influence on the: a) maximum subsidence;


Sensibility analysis at the mining depth variation

The behaviour of the model at the mining

depth variation (or the thickness of the roof rocks strata) was studied using several finite element models, for which the mining goaf was situated successively at various depths (H=100; 120; 150; 200; 300; 500; 600m).

In this case two massive zones with different characteristics were taken into consideration: first zone involves the surrounding rocks of the mined coal seam and the second zone is specific of the coal seam.

The rocks’ characteristics of these two zones, considered homogenous and isotropic, in the Mohr – Coulomb elasto-plastic behaviour are presented in Table 1.

The models results show that the subsidence and the displacement very much increase with the mining depth decrease, especially at the depth less then H=200m (Fig.6) [2]:

2216.1max1289464

HW ⋅= , R2 = 0.9945 (14)

2478.1max198247

HU ⋅= , R2 = 0.9923 (15)

W max = 289464*H -1,2216

R2 = 0,9945

0

200

400

600

800

1000

1200

0 100 200 300 400 500 600Mining depth - H (m)

Max

imum

sub

side

nce

- Wm

ax (m

m)

a)

U max = 98247*H -1,2478

R2 = 0,9923

0

50

100

150

200

250

300

350

0 100 200 300 400 500 600 700Mining depth - H (m)

Max

imum

hor

izon

tal d

ispl

acem

ent

Um

ax (m

m)

b)

Fig. 6. Mining depth influence on the: a) maximum subsidence;


The influence of the mining depth is explained by the increase of the vertical stresses (vertical and horizontal) developed in the rock massive with the depth increase, being directly proportional. Sensibility analysis at the mining height variation

At this point, it was made an analysis of the behaviour of the finite element models at the mining height variation (or coal seam thickness). In this end, there were made several calculus variants where the coal seam was mined in the inclined slices with a height equal to 2.5m; the successive cases of the modelling being for 1 slice, 2, 3 and 4 simultaneous mining slices (respectively, for a mining height of: 2.5m; 5.0m; 7.5m and 10.0m).

From the calculus on these models, it was observed that the subsidence and the displacement increase logarithmically with the increase of the slices number or with increase of the mining height (Fig.7). This demonstrates the great influence of the mining height on the main parameters of the subsidence basin [2]:

31


W max = 41,568*ln(m ) + 193,89R2 = 0,9997

220

230

240

250

260

270

280

290

300

2 3 4 5 6 7 8 9 10Mining height - m (m)

Max

imum

sub

side

nce

- Wm

ax (m

m)

a) Umax = 12,364*ln(m ) + 66,847

R2 = 0,9985

77

79

81

83

85

87

89

91

93

95

2 3 4 5 6 7 8 9 10Mining height - m (m)

Max

imum

hor

izon

tal d

ispl

acem

ent

Um

ax (m

m)

b)

Fig. 7. Mining height influence on the: a) maximum subsidence;


89.193ln568.41max +⋅= mW ,R2=0.9997 (16) 847.66ln364.12max +⋅= mU ,R2=0.9985 (17)

Sensibility analysis at the coal seam dip variation

The behaviour manner of the models (from the point of view of subsidence and horizontal displacement) in function of the dip coal seam variation was analysed in the conditions of the angles of : α = 0o; 5o; 10o; 15o; 20o; 25o; 30o; resulting 7 new models with different geometry.

After the analysis of the finite element models results, it could be observed that the maximum subsidence decreases with coal seam dip increase (Fig.8) and the subsidence basin is increasingly asymmetrical (Fig.9).

160

165

170

175

180

185

190

195

200

0 5 10 15 20 25 30Seam dip - α (o)

Max

imum

sub

side

nce

- Wm

ax (m

m)

Fig. 8. Coal seam dip influence on the maximum

subsidence

The representation of the subsidence basins in according with the coal seam dip is made in Figure 9 and the horizontal displacement curves in Figure 10.

0

20

40

60

80

100

120

140

160

180

200

0 100 200 300 400 500 600 700 800 900 1000 1100

Distance - D o (m)

Subs

iden

ce -

W (m

m)

α = 0α = 5α = 10α = 15α = 20α = 25α = 30

Fig. 9. Subsidence basins in function of the coal seam dip variation

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

70

0 100 200 300 400 500 600 700 800 900 1000 1100

Distance - D o (m)

Hor

izon

tal d

ispl

acem

ent -

U (m

m)

α = 0α = 5α = 10α = 15α = 20α = 25α = 30

Fig. 10. Horizontal displacements in function of the coal seam dip variation

Sensibility analysis at the horizontal stresses variation

The sensibility analysis of the models at the

horizontal stresses was made proceeding at successive calculus, on several models, with variable geostatic loadings, taking into consideration two regions with different characteristics (Table 1).

To analyse the model behaviour at the horizontal stresses (horizontal thrust) variation,

voxvh k σσν

νσ ⋅=⋅−

=1

, developed in rock

massive, the vertical stresses were considered constant and equal to 7989=⋅= Hv γσ KN/m2 and the parameter Kox (the horizontal thrust coefficient) having different values (Kox = 0.2; 0.4; 0.6; 0.8; 1; 1.5; 2). Thus results 7 different variants of the loadings of the finite element models.

After calculus, it was observed that the maximum subsidence and the horizontal displacement reduce linearly with increase of the horizontal stresses (Fig.11). It is worth mentioning that, in these conditions, the subsidence basin is larger for the important stresses (Fig.12).

32


Constant vertical stresses (7989 kN/m2)

W max = -0,0055*σ h + 270,92

R2 = 0,9999

180

190

200

210

220

230

240

250

260

270

1000

2000

3000

4000

5000

6000

7000

8000

9000

1000

0

1100

0

1200

0

1300

0

1400

0

1500

0

1600

0

Horizontal stresses - σ h (kN/m2)

Max

imum

sub

side

nce

- Wm

ax (m

m)

„

a)

Constant vertical stresses (78292 kN/m2)

U max = -0,0013*σ h + 89,238

R2 = 0,9995

65

70

75

80

85

90

1000

2000

3000

4000

5000

6000

7000

8000

9000

1000

0

1100

0

1200

0

1300

0

1400

0

1500

0

1600

0

Horizontal stresses - σ h (kN/m2)

Hor

izon

tal d

ispl

acem

ent

U max

(m

m)

b)

Fig. 11. Horizontal stresses influence on the: a) maximum subsidence;


By consequence, the variation of these parameters is done by the following relations [2]:

92,2700055,0max +⋅−= hW σ ,R2=0,9999 (18) 238,890013,0max +⋅−= hU σ ,R2=0,9995 (19)

The subsidence basins, related to the horizontal stresses with the previous values, are represented graphically in Figure 12, and the horizontal displacements in Figure 13.

-50

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200

Distance - D o (m)

Subs

iden

ce -

W (m

m)

Kox = 0,2Kox = 0,4Kox = 0,6Kox = 0,8Kox = 1Kox = 1,5Kox = 2

Fig. 12. Representation of the subsidence basins in the case of the horizontal stresses variation

-100

-80

-60

-40

-20

0

20

40

60

80

100

0 200 400 600 800 1000 1200

Distance - D o (m)

Hor

izon

tal d

ispl

acem

ent -

U (m

m)

Kox = 0,2Kox = 0,4Kox = 0,6Kox = 0,8Kox = 1Kox = 1,5Kox = 2

Fig. 13. Representation of the horizontal displacements in the case of the horizontal stresses variation

Ground surface deformation in the case of the underground mining of the two near coal seams

The influence of the two near coal seams on

the ground surface stability was made by a general model, which: the coal seams are horizontal and symmetrically superposed, the goafs having the same sizes and the distance between them is of 100m (Fig.14).

Fig. 14. Finite element model in the case of two

near coal seam

For this end three numerical models of calculus were generated: a model with these two coal seams in mining stage and other two models with every coal seam in independent mining stage.

The results of the calculus were synthesized in the Figures 15 and 16. In Figure 15 the subsidence is shown for these three computation cases and in the Figure 16 the horizontal displacement.

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200

Distance - D o (m)

Subs

iden

ce -

W (m

m)

Underground mining of the superior coal seam

Underground mining of the inferior coal seam

Underground mining of both coal seams Fig. 15. Subsidence basins representation in the

case of two near coal seams mining

-100

-80

-60

-40

-20

0

20

40

60

80

100

0 200 400 600 800 1000 1200

Distance - D o (m)

Hor

izon

tal d

ispl

acem

ent -

U (m

m)

Underground mining of the superior coal seamUnderground mining of the inferior coal seamUnderground mining of both coal seams

Fig. 16. Horizontal displacement representation in the case of two near coal seams mining

33


Analysing the variation of these two subsidence parameters it is obvious that the simultaneous mining of two coal seams has a more pronounced influence on the ground surface deformation; and the mining of the coal seam closer to the surface has a more important impact on the deformation parameters (subsidence and displacement) than the other coal seam situated at depth.

We note that the presented situation is a general one, very simplified; in reality, the displacement and the ground surface deformation, in the case of two or more near coal seams depend on several factors such as: the goaf sizes, coal seams dip, mining method, roof control procedure, distance between coal seams, position of the mined space, etc.

Conclusions

In view to analyse the sensibility of the main parameters of the subsidence basins (subsidence and horizontal displacement) at the variation of the geo-mining factors several 2D finite element models were made, in elasto-plasticity behaviour hypothesis, arriving at the following conclusions:

1) the apparent density or specific weight, by their contribution at the stress and strain state development, explain the pronounced sensibility of the subsidence and displacement at the variation of this parameter;

2) the subsidence and the displacement increase significantly with the elasticity modulus decrease;

3) the subsidence parameters are much less sensitive to the variation of the Poisson rate, cohesion and internal frictional angle;

4) the subsidence and displacement very much increase with the mining depth decrease, especially for the mining depth under 200m;

5) the subsidence and displacement increase logarithmically with the increase of the number of mined slices or mining height;

6) the maximum subsidence decreases with coal seam dip increase and the subsidence basin is increasingly asymmetrically;

7) the maximum subsidence and the horizontal displacement reduces linearly with increase of the horizontal stresses; in these conditions, the subsidence basin is larger for the important stresses;

8) the simultaneous mining of two coal seams has a more pronounced influence on the ground surface deformation; and the mining of the coal seam closer to the surface has a more

important impact on the deformation parameters than the other coal seam situated at depth. References 1. Hirean, C. Rocks Mechanics (in Romanian), Didactical and Pedagogical Publishing House, Bucharest, 1981, 322 p. 2. Marian, D.P. Surface Stability Analysis as Effect of Underground Mining of the Coal Seams with Gentle and Medium Dip from the Jiu Valley Coal Basin, Ph.D Thesis, University of Petroşani, 2011, 173p. 3. Oncioiu, G., Onica, I. Ground Deformation in the Case of Underground Mining of Thick and Dip Coal Seams in Jiu Valley Basin (Romania), Proceedings of 18th International Conference on Ground Control in Mining, 3-5 August, 1999, Morgantown, WV, USA, pp.330-336. 4. Onica, I. Introduction in the Numerical Methods Used in the Mining Excavations Stability Analysis (in Romanian), Universitas Publishing House, Petroşani, 2001, 156 p. 5. Onica, I. Environmental Mining Impact (in Romanian), Universitas Publishing House, Petroşani, 2001, pp.173-198. 6. Onica, I., Cozma, E., Goldan, T. Land Degradation Under the Underground Mining Influence (in Romanian), AGIR Revue, year XI, 2006, no.3, pp.14-27. 7. Onica, I., Cozma, E., Marian, D.P. Ground Surface Deformation Using the Finite Element Method, in Conditions of the Longwall Mining of The Coal Seam No. 3 - Livezeni Mine, Revista Minelor, 2011, pp. 24-33. 8. Onica, I., Cozma, E., Marian, D.P. Ground Surface Deformation as Effect of Longwall Mining of the Coal Seam No. 3 of the Livezeni Mine, Proceedings of the 22nd International Mining Congress and Exhibition of Turkey, May 11-13, 2011, Ankara, Turkey. 9. Onica, I., Cozma, E., Marian, D.P. Analysis of the Ground Surface Subsidence in the Jiu Vally Coal Basin by Using the Finite Element Method, Proceedings of 11th International Multidisciplinary Scientific Geo-Conference & EXPO SGEM 2011, Modern Management of Mine Producing, Geology and Environmental Protection, Albena, Bulgaria, 19.06.2011- 25.06.2011. 10. Singh, M. M. Mine Subsidence (Chapter 10.6), in SME Mining Engineering Handbook, SME, 1992, pp. 938-971 11. Todorescu, A. Rocks Properties (in Romanian), Technical Publishing House, Bucharest, 1984, 676 p. 12. *** CESAR-LCPC, CLEO 2D - Reference manual, V 4.0.

34


ACHIEVEMENTS AND FUTURE SOLUTIONS ON REINTRODUCING IN THE ECONOMIC CIRCUIT OF WASTE DUMPS AND DEGRADED

TERAINS BY OPEN PITS FROM OLTENIA

Cosmin Alin SMEU* Abstract: The problem of reintroducing in the economic circuit the land affected by open pit mining have to be followed since the design phase because it has a marked influence on the quarry’s limits, coefficient of stripping, and finally, the costs of extraction. Therefore, to determine the final contour of a quarry must be taken into account the interdependence between dimensions required for mining operations and the value of land expropriated, geometric parameters of the quarry and agrochemical characteristics of the surrounding and covering rocks.

This paper proposes a brief overview of current achievements in reintroducing in the economic circuit of areas degraded by quarrying activities in the basin Oltenia and identify solutions to meet the future needs of national and obligations incumbent on Romania after EU accession and the signing of numerous international environmental treaties.

Keywords: reintroducing in the economic circuit, waste dumps, quarries, degraded land, energy plants.

Introduction

Given that the tasks ahead for reuse degraded

terrains by mining activities are very large and growing, especially in the mining basins of Oltenia, where open pit mining prevailed and which continues today, there must not be spared any effort to achieve high-quality work and achieve in this way, the maximum economic effect for reusing degraded lands in each variant.

The need and advantages of reintroducing degraded lands in the economic circuit

The entire mining activity carried out from the beginning in Oltenia considered the legislative provisions on advance planning of unproductive land in equivalent surface with the area removed ____________________________________ *Ph.D student eng. University of Petroşani

from the circuit for mining needs. Unproductive land could exist in the mining area or other areas of the country where mining activity is not carried out, but there were terrains requiring accommodation.

Open pit mining, unlike the underground mining, is given options for improving the environment, particularly through development and optimal integration of waste dumps in the area’s characteristic landscape, then a suitable and effective recultivation of land on these dumps.

Among the many reasons that support the need for remodeling and rehabilitation of land affected by human activities include: - eliminating the risk of sliding the positive relief forms, occurred in an area by external storage of waste dumps; - eliminate the negative visual impact of areas with lunar aspect; - the need for reintegration of degraded lands in the circuit of production and/or ecological of the regions where they are, leading to regeneration of their economic potential; - improving environmental quality; - reduction of slopes and with it, reducing the intensity of erosion phenomena and accelerate the installation of vegetation; - possibility to create new storage spaces for various types of waste in the pits remaining gaps [3].

Degraded lands and waste dumps restoration is based on the fundamental principles of ecological restoration, namely: - the principle of globality or interdependency; - the principle of ambiental autonomy; - the principle of transparency and democracy; - the principle of compliance with the population; - the principle of economic efficiency; - the principle of minimum size and reversibility; - the principle of respect for tradition. [4] Characterization of Oltenia region

The climate is temperate continental type with Mediterranean influences, with an average temperature of 10.3° C and an average annual precipitation of 753 mm, wind regime greatly influenced by the proximity of mountains and hills, the deforestation in the area, diversion of watercourses, the emergence of temporary or

35


permanent artificial lakes and ponds, creating over time mutations in the microclimate in the mining basins of Oltenia.

The soils present in the region of Oltenia, fall in the class of low to high potential and they are selectively extracted and stored in warehouses before starting the actual extraction of overburden and lignite. Waste extracted and deposited in dumps, which has a moderate phosphorus content, moderate to high content in potassium and high pH, was shown to be suitable for restoring land made available after mining activities are stoped.

Because the chemical properties of waste materials fro the overburden is deposited in dumps, there was a rapid reinstallation of spontaneous vegetation on dumps surfaces released of technological tasks.

The first research on reintroducing in the economic circuitc of land degraded by mining in the Oltenia region began in 1968 and in 1972 was founded the first specialized unit area for redevelopment and recultivation with annual and multi-annual agricultural, forest, vine and different tree species of degraded lands by mining and their reintroduction in the production circuit.

Studies undertaken since 1968 and the results obtained led to a successful approach on land restoration activities. Achievements on reintroducing in the economic circuit of waste dumps and degraded lands

Starting from the requirements of full and

efficient use of land and taking into account the fundamental principles of ecological restoration specialists in the mining units, together with the territorial-administrative and representatives of public decided the restoration of degraded lands predominantly in agricultural and forestry puposes.

Reintroduction in the economic circuit of degraded lands by mining activity requires the redevelopment and modeling of areas and then their recultivation.

Mining redevelopment and modeling are activities that require several steps and technology, namely the recovery and conservation of topsoil, construction of waste dumps, dumps surface leveling, the improvement of the material stored in dumps, deposit the vegetal soil on the dumps leveled and improved surfaces.

General Information

Throughout the period when the quarrys were

put into service in Oltenia, about 50 years, were affected and permanently occupied 17.432 ha of which 13.591 ha of agricultural land, respectively

78% and 3.841 ha of forest, belonging especialy to the mining basin Rovinari.

Area occupied structure is as follows: 49% respectively 8.144 ha is arable land, 22% respectively 3.841 ha of forest. It is noted that about 4.560 ha or 42% of the area occupied by mining have been a natural pastures and hay fields, categories of use that provides low and unstable production. Also throughout the duration of the mining activities were affected 362 ha (2.1%) orchards and 125 ha (0.07%) living hybrid culture with a great diversity of native species and varieties.

As utilities, 68% of the total land pased in the administration and heritage of SNLO Tg. Jiu, was designed for excavation work fronts and waste dumps, and only 32% for related activities, such as adjustments of watercourses, railways, electricity networks, roads, construction of a social nature, plants, etc. (example: for Jiu river regulation and construction of an artificial lake at Rovinari, were required surfaces amounted to 1,000 ha). [1]

Generally soils affected by mining activity differs depending on geological and geomorphological conditions, their productive potential is low to medium, so that they fall in reliability classes ranging from second to fifth.

In the mining activity the soil factor disappeared even if largely the arable horizon has been selectively exploited for later uses.

Materials deposited in waste dumps are very heterogeneous in terms of physical and chemicalcomposition, are generally devoid of biological activity and are extremely diverse in terms of mineralogical (sands, gravels, clays, marls) which makes the potential for fertility small, they fall in reliability classes fourth and fifth.

Agricultural recultivation

Following investigations, on the exterior dump of Tismana quarry were made between 1981-1983 viability experiments on four crops - wheat, corn, potatoes and clover - in terms of two types of clayey earth: yellow clay and blue clay, and during 1984-1985 was made another batch of experimental crops (four crops) on Cicani - Balta Unchiaşului waste dump, which consists predominantly of yellow clays: corn, wheat, oats and clover.

The experiments were placed in a 4 year rotation, and sola with clover aimed and contributing to the enrichment of organic matter and structure of land taken into cultivation. During 1993-1994 the experiments on Cicani waste dump were resumed, this time using six types of plants: potato, corn, oats, peas, barley and mash. [1, 5]

36


Viticulture and fruit growing tree recultivation

Waste dumps from Rovinari Mining Basin offers extremely favorable conditions for varieties of fruit trees in early adulthood or extraearly adulthood. The results achieved by the Research Station on Fruit Production Tg. Jiu on Cicani waste dump showed good behavior of apple and plum, at the age of 12 - 13 years the average productions obtained were of 24.9 t/ha, respectively 8.2 t / ha, cherry production was 4.1 t/ha, and for black cherry of 3.8 t / ha, for nuts the production was sporadic and hazel has been used successfully to stabilize slopes of the quarry and Gârla wast dump.

In terms of viticulture, vine plantations near Cicani have shown that good results can be achieved through proper preparation of land, which consists of basic and annual fertilization. Vine varieties grown in the Cicani – Gârla waste dumps area achieved normal production of qualitatively and quantitatively. Are noted Feteasca Royal 12.2

t/ha, Merlot with 11.7 t/ha and Italian Riesling with a production of 10.1 t/ha. [1, 6] Forest recultivation

In the domain of forest recultivation is mentioned the afforestation done in the interior and exterior waste dumps of Gârla open pit, which occupies an area of 125 hectares, the plantation of pine in Tismana area who has 16 years of age and occupies an area of 32 ha of the external dump and 8 ha on slopes of the guard channel on the northern side of the pit, and the forests in Rovinari - Peşteana and Roşia de Jiu areas, which occupies 40 hectares.

Table 1 contains the area reintroduced in the economic circuit up to 2010, and in Table 2 the situation of the waste dumps from Oltenia and the areas occupied by them. [5, 6]

Table 1. Surfaces reintroduced in the economic circuit (2010)

Surface (ha) From wich No. Mining unit Total

agriculture forest E.M.C. Roşia 820,42 547,81 272,61 Cariera Roşia 460,64 309,23 151,41 Cariera Peşteana Nord 99,50 57,30 42,20

Cariera Peşteana Sud 119,66 119,66 0,00

1

Cariera Urdari 140,62 61,62 79,00 E.M.C. Motru 676,44 466,91 209,53 Cariera Lupoaia 256,97 163,64 93,33 2 Cariera Rosiuta 419,47 303,27 116,20 E.M.C. Berbeşti 303,80 303,80 0,00 Cariera Berbeşti Vest 75,00 75,00 0,00 Cariera Panga 185,33 185,33 0,00 3

Cariera Olteţ 43,47 43,47 0,00 E.M. Mehedinţi 217,98 0,00 217,98 4 Cariera Husnicioara 217,98 0.00 21798

TOTAL S.N.L.O. 1963,25 1097,38 865,87

37


Ta

ble

2. E

xter

nal w

aste

dum

ps fr

om O

lteni

a an

d th

e su

rfac

es o

ccup

ied

by th

em

Surfa

ce

From

wich

Su

rface

Fr

om w

ich

Supr

afaţă

Fr

om w

ich

Crt.

no.

Min

ing u

nit

Exter

ior w

aste

dum

p Pr

ovid

ed in

SE

T* or

PE*

*Fo

rest

A

gricu

lture

O

ccup

ied

Fore

st

Agr

icultu

re

To be

occu

pied

Fore

st

Agr

icultu

re

l. EM

C M

otru

Lupo

iţa

Vale

a Mănăs

tirii

Steic

(Lup

oaia

V-V

I) V

alea C

erve

niei

Bu

joră

scu

V

alea R

ogoa

zelo

r V

alea Ş

tiuca

ni

Potân

gu

69,14

55

8,95

40,18

40

,53

130,2

7 17

4,64

119,3

2 64

,02

32,15

0

19,60

32

,41

73,11

13

7,00

69,04

0

36,99

55

8,95

20,58

8,1

2 57

,16

37,64

50

,28

64,02

69,14

40

3,39

33,70

40

,53

91,06

12

3,00

119,3

2 64

,02

32,15

0

19,60

32

,41

33,90

85

,36

69,04

0

36,99

40

3,39

14,1

8,12

57,16

37

,64

50,28

64

,02

0 15

5,56

6,46 0

39,21

51

,64

0 0

0 0 0 0 33

,90

37,64

0 0

0 15

5,56

6,46 0 5,31

14,00

0 0

To

tal

1197

,05

363,3

1 83

3,74

944,1

6 27

2,46

671,7

0 25

4,87

73,54

18

1,33

2.

EMC

Peşte

ana

Peşte

aua S

ud

Peşte

ana N

ord

Urd

ari

91,79

19

5,67

86,73

0 0 15

,09

91,79

19

5,67

71,64

91,79

19

2,30

30,72

0 0 30

,72

91,79

19

2,30

0

0 3,37

56,01

0 0 56

.01

0 3,37 0

To

tal

374,1

9 15

,09

359,1

0 31

4,81

30,72

28

4,09

59,38

56

,01

3,37

3. EM

C Jilţ

Jilţ S

ud

Jilţ

Nord

66

0,73

172,7

4 19

3,48

68,06

46

7,25

104,6

8 34

4,00

137,7

4 42

,00

65,00

30

2,00

72,74

32

6,73

35,00

42

,00

0 28

4,73

35,00

Total

83

3,47

261,5

4 57

1,93

481,7

4 10

7,00

374,7

4 36

1,73

42,00

31

9,73

4. EM

C Pi

noas

a V

alea N

egom

ir 66

7,93

133,8

9 53

4,04

197 ,0

0 85

,28

111,7

2 47

0,77

337,0

4 13

3,73

Total

66

7,93

133,8

9 53

4,04

197,0

0 85

,28

111,7

2 47

0,77

337,0

4 13

3,73

5.

EMC

Roşia

Roşia

49

8,00

0 49

8,00

141,0

2 12

7,02

14,00

35

6,98

229,9

6 12

7,02

Total

49

8,00

0 49

8,00

141,0

2 12

7,02

14,00

35

6,98

229,9

6 12

7,02

6.|

EM

Meh

edinţi

Hus

nicio

ara V

est

282,6

4 0

0 12

0 ,42

81,99

38

,43

160,2

2 80

,23

79,99

To

tal

282,6

4 0

0 12

0,42

81,99

38

,43

160,2

2 80

,23

79,99

7. EM

Ber

beşti

Rugc

t O

lteţ

Berb

eşti V

est

Pang

a Sud

Pa

nga N

ord

134,0

0 14

6,00

85,00

48

,00

137,0

0

69,00

0,0

0 66

,00

0,00

37,00

65,00

14

6,00

19,00

48

,00

100,0

0

87,00

14

6,00

75,00

48

,00

88,00

47,00

66

,00

37,00

0 0

47,00

14

6,00

9,00

48,00

88

,00

47,00

0

10,00

49

,00

0

0 0 0 0 0

47,00

0

10,00

49

,00

O To

tal

550,0

0 17

2,00

378,0

0 44

4,00

150,0

0 33

8,00

106,0

0 0

106,0

0 To

tal ge

nera

l 44

03,26

94

5,83

3174

,8 26

43,14

85

4,47

1832

,68

1769

,95

818,7

8 95

1,17

38


Future solutions for reintroducing in the economic circuit of waste dumps and degraded lands

During the next decade, quarrys in mining basins of Oltenia will record notable changes in their overall geometry, due to changes in the method of operation by switching to interior waste deposits and also by using a higher proportion of transhipment of waste materials in dumps. Meanwhile, some quarrys will be closed due to depletion of reserves from the fields and we will see greater concentration of production in several bigger ones. This will result in reduction of areas taken out of the economic circuit and an increase of the surfaces rehabilitated and reintroduced in the economic circuit.

In conjunction with the production needed to be ensured for national economy and with the

concrete technical and mining operation conditions in the quarrys, the dynamic of the occupied land and the reclaimed one for economic purposeis presented in Table 3. [2]

The analysis of the table shows that surfaces arranged and reintroduced in the economic circuit will be larger by 4.000 ha, compared to those occupied by mining activities in the period under review.

Reintroduction of degraded lands in the economic cycle will always respond to local owners interests and will be based on experience gained so far by the authorities and Romanian specialists in this field.

Selecting crops and plantations possible to apply in the future will be made taking into account the climate, the nature of the land and the positive experience gained in the field so far.

Talel 3. Dynamic of occupied lands and surfaces reintegraed in thr economic circuit (2009 - 2017)

Alternatively to the set presented (agricultural, forestry, vine or fruit growing recultivation) is the technical crops.

Of these a category with high potential for cultivation in Oltenia and a more wide-scale use in developed countries are the energy plants, namely energy willow. The opportunity to cultivate energy plants

Energy plants are used as fuel in heat/electric power generation.

By replacing fossil fuels they have the potential to reduce carbon dioxide emissions of greenhouse gases. Growing energy plants is required for Romania because:

- is part of the Kyoto Protocol to reduce greenhouse gas emissions by 12.5% in 2012 compared to 1990;

- must meet targets on shares of electricity production from renewable sources.

These things provide a significant opportunity for energy crop industry.

At this moment in Romania there are no wood energy crops planted, if not taken into account forest lands with various species of trees for industrial exploitation of which must pass dozens of years of their establishment. This proposal is primarily concerned with the energy willow crops, giving so far the best annual returns per hectare and allowing timber harvesting annualy or biennialy in good economic conditions.

As part of the complete chain of energy production from renewable sources, must be taken into account that is allocated three green certificates for electricity from biomass, according to Law 220/2008. which finally brings a significant added value for the entire system plantation - energy delivery.

Figure 1 shows the general scheme of power generation using energy plants (biomass).

39


Fig. 1. The process of power generation using biomass

Proposals on the recultivation of degraded land with dumps and power plants

Energy crops consisting of varieties of willow ,dense planted, with a high yield with a harvest cycle of 1-2 years are most suitable for dumps and degraded lands from activities in the Oltenia mining basin.

Osier, a willow variety that grows in the form of a bush (Fig. 2.), is the basis of most varieties of willow planted for energy purposes. Energy willow is a wood culture, perennial, rhizomes or shoots remaining in soil after harvest, growing new branches next spring.

A plantation can be viable for 30 years before the need for replanting, this is according to productivity stalks.

Energy willow is planted in spring using planting material from specialist manufacturers and equipment for these purposes.

Willow will grow rapidly in the first year, reaching up to 4 m high. In the winter after planting, the stalks are cut from the ground to encourage the growth of several shoots, like a bush. Thr harvest normally occurs in winter, two years after the first cutting. The equipment used for harvesting is specially designed for such purposes and depends on the specifications required by the end customer in terms of biomass used. Most operations, except for planting and harvesting, are carried aut by using ordinary farm equipment.

Efficiency will depend very much on the type of soil and crop establishment efficiency.

40


Fig. 2. Plantations of energy willow and harvesting method

Willow roots, which are fibrous in nature, they

penetrate deep into lands drainage and therefore it is recommended that willow to be planted at least at 30 m away from any drains which are considered important. When choosing an area must be considerd the life of the drainage system in connection with a projected life of willow culture.

To ensure economic efficiency of the culture must consider at least 3 ha for each plot. The best plots are those that minimize the need for short lengths of the lines or require changes in direction during field operations. The choice of lands that can be economically harvested is crucial. For easy operations would be ideal a plane terrain or with a slope of max. 7%. It is recommended that the slope of the land does not exceed 15%.

There must be ways to access for all the necessary equipment available during the establishment or harvesting of culture (Fig. 2). Width of access roads must be at least 4.5 m, but if it creates new ways to access it is recommended that this width to be 7.5 m. It must be taken into account the height of bridges or weight supported by access roads where necessary. The ideal areas for the transfer or storage of the crop must be adjacent to plantation areas. Requirements on the structure of planting site

The structure of the planting site must take account of operational requirements. Wedge heads are required of min. 8 m in width at both ends to allow vehicles to turn. Where will be used a single trailer, or the harvesters have included a trailer, the length of rows should be restricted to max. 200 m to avoid the need to go in reverse along the rows for download. Where there will be present two or more trailers teh rows can be longer. However, where applicable treatments using liquid sludge from a cord, the maximum line length should be 400 m.

Accessibility of 4 m must be left along the plot edges to allow access for vehicles that spreads insecticides against willow beetles.

The effective preparation of the soil for willow planting is considered important. Considering that this culture is spread over a long period, is

perennial, providing ideal conditions for its establishment will benefit by having good first and following harvests.

Weed control is a critical part of crop establishing. The complete eradication of all invasive perennial weeds is essential before planting. One or two applications of herbicide based on glyphosat in concentrations well established, must be made in summer/autumn prior to planting. Ideal first application of herbicide should be mid-summer followed by another application to control any renewal fall weeds. An additional application before spring planting may be needed on some lands. Appling herbicides only in spring will not be highly efficient.

If the land required will be needed scarifying to a depth of 40 cm to decompact the soil. Then it is needed to be make a plowing to a depth of 25 cm and leave during autumn/winter.

On light land a spring plowing is better to be done. Loosening the soil should be done immediately before planting.

Sludge, prepared manure, or other organic fertilizer with low nitrogen content can be incorporated into the soil before plowing. This is especially beneficial on light soils where moisture will increase retention and help conditioning the soil.

If rabbits are present, they must be kept away from the plantation at least the first two years until the first harvest, to allow the crop to mature after the stage when is vulnerable. In this purpose special fences may be raised against rabbits. Conclusions

In Romania there are over 40 years experience in planning and reintroducing in the economic circuit of areas degraded by mining.

So far there have been reintroduced in the economic cycle, with good results, only in the mining basins of Oltenia, over 3.000 ha.

There have been studied over the years plantings and adequate crops to the new climate and soil conditions, establishing the best species of

41


trees and plants that will be used in future, in areas rebuilt after mining.

Depending on the necessary production of lignite to achieve and concrete conditions that will perform the work of extraction, were planned for the next ten years to be reintroduced in the economic circle of surfaces, so as to significantly reduce the gap between the areas of degraded lands and those introduced into the economic circuit.

It is expected that future technical plant crops (energy plants in this case) will replace traditional crops (agricultural, orchards, vineyards and forest) as the best option for rehabilitation of degraded lands and waste dumps from Oltenia mining basin.

This version has some economic advantages but also presents an advantage to align the environmental and energy policies from Romania to those in European Union in compliance with international agreements signed in the last 21 years.

The recovery of land affected by open pit lignite exploitation in Oltenia - Romania is in progress, so that problems of environmental restoration for the Romanian state is one of the key concerns.

References: 1. Fodor, D., Baican, G. Impact of Mining on the Environment (in romanian), INFOMIN Publishing House, Deva, 2001. 2. Fodor, D. Exploatarea in cariere a zacamintelor de substante minerale si roci utile, Editura CORVIN, Deva 2008. 3. Lazăr, M. Environmental Restoration (in romanian), Universitas Publishing House, Petrosani, 2001. 4. Lazăr, M. Rehabilitation of Degraded Lands (in romanian), Universitas Publishing House. Petrosani, 2010. 5. Baican, G., Huidu, E., Ianc, I. "Reintroducing in the Economic Circuit of the Areas of Land Affected by the Exploitation of Lignite at CNLO Tg. Jiu (in romanian), Romania." Trends in the Restructuring of Coal Industry in Central and Eastern European countries - 29th-30th, May 2000, Sinaia, Romania. 6. Baican, G., Boldor, C., Ianc, I. "Rehabilitation of Waste Dumps Resulting from Mining Lignite in Open Pits from Oltenia Mineral Basin" (in romanian), IV World Congress of Environmental Mining 25 to 30 June 2001, Baile Felix Romania.

42


THE POSITIONAL SYNTHESIS OF THE SLIDER-CRANK MECHANISM

Vasile ZAMFIR*, Horia VÎRGOLICI**, Olimpiu STOICUŢA***

Abstract. In the paper we present the positional synthesis of the slider-crank linkage as part of mining machines and equipment.

Introduction

The notations in fig. 1 will be used for the slider-crank mechanism:

Fig. 1 The slider-crank mechanism and the parameters

defining it

r – crank AB length; l – connecting rod BC length;

0AAa = - eccentricity value;

CCs 0= - slider displacement against original position C0 (variable dimension);

00CAh = - parameter indicating the initial position C0 of the slider A0 (constant dimension);

φ0 – crank initial positioning angle, considered counterclockwise (constant dimension);

φ – crank rotation angle, measured in the same direction with φ0, against the line AI (variable dimension).

The function to be approximated is the following: s = F(φ).

The mechanism position equation is obtained writing the contour vectorial equation:

srhal −++= (1)

Squaring, we get:

0)sin(2

)cos(2)cos(22222

0

0022

=−++++

++++−−+

larar

rsrhshhs

ϕϕ

ϕϕϕϕ(2)

____________________________________ * Prof.eng. Ph.D – University of Petroşani **Lect. Ph.D - Univ. „Spiru Haret” Bucureşti *** Asist.eng. Ph.D – University of Petroşani

The slider-crank mechanism is determined by five geometrical parameters a, r, l, h and φ0. The same calculus model will be used for determining them as the one used for the synthesis of the four-bar linkage. The calculation of three parameters

Equation (2) will be written as the following polynomial (similar to that used at the synthesis of the four-bar linkage):

0)()()( 221100 =+++ ϕϕϕ fpfpfp (3)

The case of determining parameters a, h and l (r and φ0 being chosen arbitrarily)

In order to facilitate calculations, it will be taken r = 1, considering a, h and l as relative values, obtained in relation to the crank length r. In this case the polynomial terms (3) have the following expressions:

⎪⎪

⎩

⎪⎪

⎨

⎧

=−=

−++=

aphp

lhap

2

1

222

0 21

(4)

⎪⎪

⎩

⎪⎪

⎨

⎧

+=++=

++=

)sin()()cos()(

)cos(2

)(

02

01

0

2

0

ϕϕϕϕϕϕ

ϕϕϕ

fssf

ssf (5)

The remaining calculations are similar to those in the case of the four-bar linkage.

The case of determining parameters a, r and l (h and φ0 being chosen arbitrarily)

Parameter h will be considered equal to unit (h=1), and a, r, l taken as relative values in relation to h.

In this case, the terms of polynomial (3) have the following expressions:

⎪⎩

⎪⎨

⎧

==

−++=

arprp

larp

22

1

2

1

2220

(6)

⎪⎩

⎪⎨

⎧

+=+−=

−=

)sin()()cos()1()(

2)(

02

01

20

ϕϕϕϕϕϕ

ϕ

fsf

ssf (7)

Then we proceed as in the preceding case.

43


The calculus of four parameters

Determining parameters a, r, h and s (φ0 being chosen arbitrarily)

Parameter φ0 is chosen arbitrarily. In this case the interpolation polynomial is the following:

0)()()()()(

4433

221100

=++++++

ϕϕϕϕϕ

fpfpfpfpfp

(8)

and the terms used in relation (8) have the appearance:

⎪⎪⎪⎪

⎩

⎪⎪⎪⎪

⎨

⎧

−==

−=

=−=

−−−=

rhlppp

rlp

hpap

rharlp

324

3

2

1

2222

0 2

(9)

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

−=

=

+−=+=

+−=

sf

sf

ff

sf

)(2

)(

)cos()()sin()(

)cos()(

4

2

3

02

01

00

ϕ

ϕ

ϕϕϕϕϕϕ

ϕϕϕ

(10)

The coefficient p4, being a combination between coefficients p2 and p3, the system (10) becomes non-linear in pj; j=0,1,2....

The case of determining parameters a, r, l and φ0 (h being chosen arbitrarily)

Parameter h is chosen arbitrarily. Functions sin(φ0+φ) and cos(φ0+φ) are developed in equation (2). After ordering and grouping, the terms are identified with those of the interpolation polynomial (8). The following expressions are obtained for the terms involved:

⎪⎪⎪⎪⎪

⎩

⎪⎪⎪⎪⎪

⎨

⎧

=−=

=

−=

=

−−=

320

4

3

02

01

0

222

0

1

cos21cos2

ppa

tgp

ap

tgpar

p

ararlp

ϕ

ϕϕ

ϕ

(11)

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

−=−=

=−=

=

ϕϕϕϕ

ϕϕϕ

ϕϕ

sin)()(cos)()(

cos)()()(

sin)(

4

3

2

21

0

shfshf

fshf

f

(12)

The coefficient p4 being expressed as product of the coefficients p2 and p3, the system will be non-linear in pj; j=0,1,2.... The calculus of five parameters

In this case, the position equation is similar to the equation in the case of the four-bar linkage:

0)()()()()()(

554433

221100

=+++++++

ϕϕϕϕϕϕ

fpfpfpfpfpfp

(13)

The terms have the expressions:

⎪⎪⎪⎪

⎩

⎪⎪⎪⎪

⎨

⎧

=====

−=

ϕϕϕϕϕϕ

ϕϕ

ϕϕ

sin)(cos)(

cos)()()(

sin)(

5

4

3

2

21

0

ff

sfsfsf

f

(14)

⎪⎪⎪⎪⎪⎪

⎩

⎪⎪⎪⎪⎪⎪

⎨

⎧

+−=

−==

−=

−=

−++=

)1(2

sin

sin21

sin2

23

1

2435

04

03

02

01

0

2222

0

pp

pppp

ctghapctgp

rhp

rp

rlhrap

ϕϕ

ϕ

ϕ

ϕ

(15)

In this case coefficient p5 is a combination of four coefficients p1, p2, p3, p4, and the functions fi(φ) have a simple structure.

Then we proceed as in the previous case.

Remark. The calculation sequence for each case develops as follows:

- The abscissas of the interpolation nodes φj are chosen arbitrarily on the interval (φ0, φm) or by Chebyshev spacing;

- The mechanism position equations are written for these points, obtaining linear systems in the coefficients pj, j=0,1,2,..., which are solved;

- After the calculation of the coefficients pj, j=0,1,2,..., the geometrical parameters required in each case are found. For example, for the case of five parameters, finding them has the following sequence:

⎪⎪⎪⎪

⎩

⎪⎪⎪⎪

⎨

⎧

−++=+=

−=

=

=

00222

34

1

2

01

30

sin2

sin21

ϕ

ϕ

ϕ

rphralhppa

pp

h

pr

pctgarc

(16)

44


- The magnitude of the structured error is calculated (as it has been calculated for the four-bar linkage). In order to do it, the real displacement of the slider from the initial position C0 is first found, using the following relation (fig.1):

[ ]202

0 )sin()cos( ϕϕϕϕ ++−±+−= ralrhsr (17)

- The value of the function to approximate s=F(φ0+φ) is calculated;

- The condition that the approximation deviation should satisfy the relation is checked:

ar ssss Δ≤−=Δmax (18)

where Δsa is the allowable deviation.

Supplementary conditions

As in the case of the four-bar linkage for the slider-crank, too, it is required that the relative length of the elements should be within two limits L

and L1

, while the minimum transmission angle

should not be less than the minimum allowable value.

Moreover, the crank condition is checked. Let us consider the crank length equal to unit,

r=1. The other relative lengths of the mechanism elements have to verify the following inequalities:

⎪⎪⎪

⎩

⎪⎪⎪

⎨

⎧

≥⋅≤

≤≥

≥≤

LllLa

LlL

aLlaLa

1;

1

; (19)

The transmission angle of the mechanism γ is shown in figure 2. This is formed between the direction of point C absolute velocity VC and the direction of relative velocity VCB.

Fig 2. Slider-crank transmission angle

From Fi it results:

)90sin()sin( 00 γϕϕ −=++ lar (20)

la )sin(

cos 0 ϕϕγ

++= (21)

From relation (21), knowing that 1)sin(1 0 ≤+≤− ϕϕ , we deduce:

a) For a > 0:

la

la 1cos;1cos maxmin

−=

+= γγ (22)

b) For a < 0:

la

la −

=+

−=1cos;1cos maxmin γγ (23)

Writing down the value of the allowable transmission angle with γad and knowing that the cosinus function sign is of no importance, we infer:

1cos +≤ al adγ (24)

In order to have a crank, the alignment condition of the pairs B, A, C must be fulfilled (see fig. 3):

1−< la (25)

If condition (25) is not fulfilled, the mechanism will be of the slider-lever type.

From the inequalities (24) and (25) it results that for the slider-crank mechanism, the following inequalities are to be fulfilled so as to have a crank and available transmission angle:

lal ad <+≤ 1cosγ (26)

Fig. 3 The crank condition for the slider crank

mechanism

Numerical example

Let us synthesize a slider crank mechanism for 5 accuracy points, for the function:

)853531.0(145916.1)( ϕϕ ⋅⋅= arctgF (27) on the interval φ0=00, φm=800.

45


Solution The abscissa of the interpolation nodes are chosen by Chebyshev spacing:

003

001 3

002 3

004 3

005 3

402

cos 1,9582 10

3cos 16,4892 10

3cos 63,5112 10

cos 78,0422 10

m

m

m

m

m

ϕ ϕϕ

ϕ ϕ πϕ ϕ

ϕ ϕ πϕ ϕ

ϕ ϕ πϕ ϕ

ϕ ϕ πϕ ϕ

+⎧ = =⎪⎪

−⎪ = − =⎪⎪ −⎪ = − =⎨⎪

−⎪ = + =⎪⎪

−⎪ = + =⎪⎩

(28)

The system (13) (with the explanatory relations (14) and (15)) of five linear equations with five unknowns 4,0, =jp j is solved, obtaining the solutions:

0

1

2

3

4

0.8790.572

1.7731.1940.314

ppppp

=⎧⎪ =⎪⎪ = −⎨⎪ =⎪⎪ =⎩

(29)

The unknown geometrical parameters of the synthesize linkage are calculated with relations (16) in the following sequence:

00 72.548

0.9161.549

0.3921.362

rhal

ϕ⎧ =⎪

=⎪⎪=⎨

⎪ = −⎪⎪ =⎩

(30)

Taking n values, inclusively the values of the nodal abscissa of si on the interval [s0,sm], with relation (17) the value of displacement sr can be determined and then it is found the value of deviation

0( ) ( ; , , , , ) ( ), 1,i i is s f s a r l h F s i nϕΔ = − = (31) whose magnitude is compared to the values of the allowable deviation Δsa, relation (18). In fig 4.are represented the approximate and approximated functions (which are, practically identical).

Fig. 4 The approximate and approximated functions

Fig. 5 The error curve

References

1. Artobolevski, I.I., Levitski, N.I., Cercudinov, S.A. Sintez ploskia mehanizmov, Fizmatigiz, Moskva, 1959.

2. Beleţki, V Rasciot mehanizmov maşin avtomatov piscevâh proizvodstv, „Vişa scola”, Kiev, 1974.

3. Cercudinov, S.A. Sintez ploskih şarnirnorîciajnîh mehanizmov, Iz-vo Academii Nauk S.S.S.R., Moskva, 1959.

4. Dancea, I. Programarea calculatoarelor numerice pentru rezolvarea problemelor cu caracter tehnic şi de cercetare ştiinţifică, Ed. Dacia, Cluj-Napoca, 1973.

5. Hartenberg, R.S., Denavit, I., Kinematic Synthesis of Limkage, McGraw-Hill Series in Mechanical Engineering, New York.

6. Lazaride, Gh., Stere, N., Niţă, C. Mecanisme şi organe de maşini, Ed. Didactică şi Pedagogică, Bucureşti, 1970.

7. Sarkisean, Iu.L, Cecean, G.S., Optimalnîi sintez peredatocinovo cetîrzvenika, Maşino-beledenie, nr.3, 1969.

8. Tesar, D. The Generalized Concept of Three Multiply Separated Positions in Coplanara Motion, Journal of Meechanisms, vol.2, 1967, p.461-474.

9. Tesar, D. The Generalized Concept of Four Multiply Separated Positions in Coplanara Motion, Journal of Meechanisms, vol.3, 1968, p.11-23.

10. Zamfir, V., Albăstroiu, P. Mecanisme şi organe de maşini. Partea I. Mecanisme, Litografia Institutului de Mine, Petroşani, 1975.

11. Zamfir, V. Sinteza mecanismelor cu bare articulate plane (Note de curs), fasciculele 1-5, Litografia Institutului de Mine, Petroşani, 1976, 1977.

46


BOOK REVIEW

GRAVEL PITS AND QUARRIES (in romanian BALASTIERE ŞI CARIERE)

Author Prof.eng. Ph.D DUMITRU FODOR

For some time now, it has become necessary to develop a work meant to complete the gaps of the specialized literature of the mineral rocks and useful rock exploitation and beneficiation field. Why? Because there are more than 2,000 gravel pits and useful rock quarries in Romania, at present, some of them being of national importance while others are regionally and locally important and more than 150 millions of mineral rocks and useful rocks are being mined out on annual basis. Who else, if not Prof. Ph. D Engineer Dumitru Fodor, could have filled this gap? The founder of the Romanian school of open pit mining , the author of numerous specialized books, well-known at national and international level for his contribution to the mining sciences , professor Dumitru Fodor, member of the Romanian Academy of Technical Sciences gives us the paper Gravel Pits and Quarries addressed to all those who want to learn more about quarry exploitations, and particularly to the technical – engineering staff of production, research and designing institutions who wish to improve their knowledge in the field of gravel pits and raw material and useful mineral quarries. The paper deals, theoretically and practically, with the vast theme of mineral rock and useful rocks exploitation and beneficiation of gravel pits and useful rock quarries in compliance with the newest achievements of world mining science and techniques.

47


With an original remarkable structure, the paper includes all the notions and instruments which someone need to become an expert of mineral rock and useful rock exploitation and beneficiation. Although the author has not made a distinct separation within the paper, it has been noticed that it is divided in four parts – the paper having 475 pages and 20 chapters. The first part is presenting general issues and contains some geological considerations, a presentation of the main categories and types of rocks and mineral raw materials used in different fields of activity, general data about the quarries, dimensions of geometry elements of the benches, quarry opening, preparation and exploitation, trenching, etc. The second part deals only with the gravel pits and all the issues which could raise the interest of an investor in this field of activity: formation of placer deposits, exploitation methods, equipments, mining technologies (mechanized, draglines) official instructions and loading of sands, gravel and ballast. The third part which represents a significant component of the paper deals with the hard useful rock quarries, addressing the prospecting, exploration, exploitation and extraction as blocks and monoliths using either the explosives or mechanized equipments , their processing and use in different fields of activity up to their haulage. As for the four part of the paper, it deals with environmental protection and the author is presenting several solutions to work out the management of waste resulted at the gravel pit and quarry exploitation, work security and occupational health within these mining projects and the presentation of the legislative requirements and regulations concerning the useful rock prospecting, exploration and exploitation . To make the paper useful and accessible to the skilled reader, the author, in his well – known manner, attached to the written part, several drawings, sketches and pictures as well as numerous relevant synthesis tables. It is to be noted that the calculation formulas which could not be missing from such a paper, have been so well simplified and explained that they are accessible even to those who are not engineers. The whole paper is easy to read, it can be understood by all those who want to consult it, but it is particularly valuable for those who want to start up or continue their activity in the field of mineral and useful rocks exploitation. Finally, I can only thank Professor Dumitru Fodor for he offered a new book to us all who are operating in the beautiful and indispensable mining sector.

Prof.eng. Ph.D Mircea Georgescu

University of Petroşani

48


nr. 3 EN/2011

Documents

Transcript of nr. 3 EN/2011