GEOTECHNICAL SOCIETY OF IRELAND NEWSLETTER … · existent creep-like motions. ... Best...
Transcript of GEOTECHNICAL SOCIETY OF IRELAND NEWSLETTER … · existent creep-like motions. ... Best...
GEOTECHNICAL SOCIETY OF
IRELAND NEWSLETTER
WINTER 2014
Editor’s Note
Welcome to the latest edition of the Geotechnical Society of Ireland (GSI) newsletter. The purpose of this newsletter is to provide the geotechnical engineering community throughout Ireland with an up-to-date source of geotechnical news and to provide details of upcoming events.
If you are aware of a project of interest, recent research output or an upcoming event which you would like included in the next edition of the newsletter, please contact Maurice Ryan ([email protected]). All contributions would be greatly appreciated.
The GSI Committee
The GSI activities and events are organised and managed by a committee of geotechnical engineers working in Irish industry and academia. As this is the first edition of the newsletter since 2012, a brief introduction to the committee members is included below. If you are interested in taking a more active role in GSI events or joining the committee, please contact a committee member.
Fintan Buggy – ROD (Chairman)
Paul Quigley – ARUP (Secretary)
Michael Robinson – Test Consult
(Treasurer)
Maurice Ryan – Byrne Looby Partners
(Public Relations Officer)
Brian Byrne – Carlow IT
Ciaran Reilly – JB Barry
Cormac Reale – UCD
David Gill – AGL
Derek Luby – SLR Consulting
Gerry Stanley – Geological Survey of
Ireland
Kevin Flynn – AGL
Mark Condron – RPS
Paul Doherty - GDG
Paul Quigley – IGSL
Upcoming Events:
This upcoming season proves to be an
exciting and interesting year for
geotechnical events and conferences. The
table below details the upcoming events
of interest. Of particular note are the joint
GSI and IAH evening lecture and the GSI
half day seminar to be held during April
2015, both of which are free to attend and
usually present interesting topics of
practical significance.
Date Description Venue
GSI Events
February 2015 Joint GSI / IAH Evening Lecture
Engineers Ireland, 22 Clyde Road
Thursday 23rd April 2015
GSI Half Day Seminar Prof. Eduardo Alonso
Engineers Ireland, 22 Clyde Road
International Conferences / Events
10th December 2014
Fleming Award Evening
ICE, London
14th January 2015
John Mitchell Award Evening
ICE, London
18th March 2015
55th Rankine Lecture
Imperial College, London
13 – 17th September 2015
XVI European Conference on Soil Mechanics and Geotechnical Engineering
Edinburgh
TBC European Young Geotechnical Engineers Conference
Durham, UK
Please note that these dates are provisional –
please check for updates prior to event.
Coming Soon GSI Half Day Seminar
The upcoming GSI Half Day Seminar
promises to build on the success of the
inaugural event held in 2014. The GSI
Committee have secured Prof. Eduardo
Alonso of the University of Catalunya,
Barcelona as the keynote speaker, with
Prof. Alonso presenting a lecture on the
topic of Rapid Landslides.
Landslide displacements and velocity in
nature are often moderate, but known
cases of high velocity (>10 m/s) have
attracted considerable attention following
some extremely destructive cases in the
past.
The lecture shall cover topics including the
derivation of practical criteria to estimate
the risk of rapid slide acceleration, the
scale effects and the relationship between
the triggering of a rapid landslide and pre-
existent creep-like motions.
Further details on Prof. Alonso’s lecture
and the other topics to be covered during
the seminar shall be circulated closer to
the event.
Recent Events and Awards Civil Engineering Research Association in Ireland Conference
The Civil Engineering Research Association
of Ireland (CERAI) was established in 2012
arising out of a desire to broaden the
scope of the already successful Bridge and
Concrete Research in Ireland (BCRI)
conference series. The Association’s first
Civil Engineering Research in Ireland
(CERI) conference was recently hosted to
a very high standard by Queen’s
University Belfast. One of the highlights of
the two day event was an exquisite
conference banquet in Belfast City Hall.
Over 80 papers were presented covering a
diverse range of civil engineering topics.
The geotechnical keynote lecture was
given by Prof. Bob Gilbert of The
University of Texas at Austin and was
entitled “Opportunities for Innovation in
Offshore Geotechnical Engineering”.
There were 12 geotechnical papers
presented at the conference, with the
award for Best Paper going to Ciaran Reilly
and Trevor Orr for their paper “A novel
triaxial testing procedure to model the
action of lubricants in pipe jacking” and
Best Student Paper in Geotechnics to Luke
Prendergast, Ken Gavin and Paul Doherty
for their paper "The effect of scour on the
dynamic response of an offshore wind
turbine".
The Proceedings will be available for
download from www.cerai.net. The next
CERI conference will be held in Galway in
2016.
23rd European Young Geotechnical Engineers Conference
In September 2014 Brian Sheil and Martin
Timoney, both from NUI Galway,
represented Ireland at the 23rd European
Young Geotechnical Engineers Conference
(EYGEC) held in Barcelona, Spain.
Nearly 50 delegates, both researchers
and practitioners, from across Europe
attended the conference presenting on a
variety of geotechnical themes.
Conference Delegation
The papers presented covered a wide
range of topics including piling,
tunnelling, ground improvement,
numerical modelling, rock stability,
geothermal applications and
geotechnical risk management, with
results from laboratory experiments,
numerical analysis and field projects
presented.
Congratulations to Audrey Hucket
(France) on winning the best overall paper
for her experimental and numerical work
on the design of geosynthetic
reinforcements overlying sinkholes. The
proceedings for the conference have
been made freely available to download
from EYGEC Proceedings 2014.
Finally, the Irish delegates are very
grateful to GSI for providing them with the
opportunity to attend and present at the
conference.
Irish Delegates:
Brian Sheil, NUI Galway; Multi-directional
loading of a monopile foundation: finite
element modelling.
Martin Timoney, NUI Galway; Strength
verification of soil-cement columns; a
scale laboratory investigation of the Push-
In Resistance Test.
Congratulations
Geotechnical Engineer Sean Mason FIEI,
Director of ground and maritime
engineering at Arup Ireland, was awarded
Best Paper/Presentation at the Engineers
Ireland Excellence Award 2014. Sean’s
paper, entitled ‘Greystones Harbour – Civil
and Maritime Works’ was presented at
Engineers Ireland headquarters, and
subsequently due to popular demand at
the Royal Dun Laoghaire Yacht Club. The
paper provides an overview of the project
from bid stage through planning and
design to construction completion.
Geotechnical challenges and opportunities
are covered, including keeping an old
landfill within the site, managing
settlements of precast concrete block
breakwaters, value-engineering the site by
operating a borrow pit within the site to
maximise re-use of dredged materials,
and the state-of-the-art use of beach
nourishment to manage coastal erosion.
Greystones Harbour Congratulations also to Dr David Gill of
AGL Consulting, who was also one of only
three shortlisted for the award for his
paper entitled ‘Geotechnical Properties of
the Dublin Port Clay’, on behalf of the
Geotechnical Society.
Information and Useful Resources
ISSMGE Bulletin The International Society for Soil
Mechanics and Geotechnical Engineering
(ISSMGE) is the pre-eminent professional
body representing the interests and
activities of Engineers, Academics and
Contractors worldwide that actively
participate in geotechnical engineering.
The ISSMGE provides useful information
and platforms for the discussion and
review of various geotechnical related
items. The ISSMGE recently published its’
bimonthly bulletin which is available for
download from
ISSMGE_Bulletin_October_2014.
ISSMGE Technical Committees In order to engage ISSMGE members
across the array of geotechnical subjects,
the ISSMGE has set up various Technical
Committees to facilitate debate and
discussion.
The mission of the ISSMGE TCs is to
provide a forum for active participation by
the individual members of ISSMGE, and to
promote the objectives, activities and
results of the technical committees
throughout the ISSMGE membership. The
TCs are a meeting arena for discussing,
developing and applying specialist
geotechnical knowledge related to the
behaviour of geo-materials, geotechnical
engineering and engineering for society. A
list of the technical committees is
available at ISSMGE Technical
Committees.
The following GSI members hold active
positions on several ISSMGE TCs. Should
any other members wish to engage with
the technical committees please contact
Fintan Buggy ([email protected]).
Name ISSMGE TC Membership
Bryan McCabe
TC306 – Geo-Engineering Education
Fintan Buggy
TC202 – Transportation Geotechnics
Mike Long
TC102 – Ground Property Characterisation from In-Situ Tests TC214 - Foundation Engineering for Difficult Soft Soil Conditions
Declan Philips
TC306 – Geo-Engineering Education
Kenneth Gavin
TC209 - Offshore Geotechnics TC212 - Deep Foundations
Trevor Orr
TC205 - Safety and serviceability in geotechnical design
Case Studies and Interesting
Projects
River Dargle Flood Defence Scheme –
Works at La Vallee Bray
Works are nearing completion on a section of the River Dargle Flood Defence Scheme at the La Vallee complex in Bray. This project involved the construction of new flood defence and erosion protection walls along the banks of the Dargle over a 300m long section of the river channel, and the placement of a 1.4 m deep layer of rock armour along the bed of the river to protect against scour. The works were required to arrest the deterioration of the existing rock armour revetment along the left bank of the river, in front of the apartments and office building in the La Vallee complex, and to upgrade the existing erosion protection measures along the right bank of the river. The works were also required to re-profile the river channel to regulate river flows under extreme flood conditions and to reduce the high flow velocities to an acceptable level.
Installation of Tie-back Anchors The scheme is a Design and Build contract and is currently being constructed by Jons Civil Engineering Company Ltd. AGL Consulting are the principal designers and
geotechnical engineers for the scheme. Structural and hydrological designs were provided by O’Shea Consulting and Fluvio R&D respectively. The Employer is Wicklow County Council (formerly Bray Town Council) and Halcrow Barry are the Employer’s Representatives. The project is funded by the Office of Public Works for Wicklow County Council. The sheetpile retaining wall along the left bank is 300 m long, including the transition zones at either end. The design of the wall was governed by the requirement to excavate up to 1.4 m below design river bed level in the temporary condition with 4 storey office and residential buildings within close proximity to the wall. The retained heights ranged from 6.25 m–7.5 m. A total of 118 No. ground anchors ranging in length from 13.5-17.0m were installed at 2.4 m centres at 40° to the horizontal along the wall to provide lateral support in the temporary and permanent condition. The depth of the sheetpiles was governed by hard driving into weak weathered rock under strict controls for noise and vibration. In some places the sheetpiles did not achieve the required depth of toe penetration and temporary props were required at bed level to complete the dig for the scour protection. Sheetpiles were also installed along the right bank over a distance of 290 m along the river channel. The majority of the sheetpiles were constructed as a cantilever wall for a temporary retained height of 3.4 m to support the banks for the dig to install the scour protection. A 75 m section of the wall cut into the toe of a previous landslide on the right bank so the sheetpiles along this section of the wall were driven to rock at a depth of about 9.0 m and the wall was supported
by 22 No. 18.0 m long ground anchors which were installed at 3.6 m centres along the wall at 45° to the horizontal to provide a 5.0 m socket in rock. All of the design and construction work was completed within an extremely tight programme to complete the work in the river channel between the second week of July and the first week of November, with a project specific derogation from Inland Fisheries Ireland to work beyond the end of September. This posed many logistical constraints to coordinate all of the machinery and equipment within a narrow river channel which was prone to rapid flooding during periods of heavy rain. The project is now very close to completion with all works in the river bed completed and final landscaping underway.
Works Nearing Completion – Oct 2014
Dr Breiffni Fitzgerald (AGL Consulting)
Geotechnical Inspections in Dhaka,
Bangladesh
On 24 April 2013, Rana Plaza, an eight-story commercial building, collapsed in Savar, a sub-district in the Greater Dhaka Area, the capital of Bangladesh. The search for the dead ended on 13 May with a death toll of 1,129. Approximately 2,515 injured people were rescued from the building alive. It is considered the deadliest garment-factory accident in history, as well as the deadliest accidental structural failure in modern human history.
The building contained clothing factories, a bank, apartments, and several other shops. The shops and the bank on the lower floors immediately closed after cracks were discovered in the building. Warnings to avoid using the building after cracks appeared the day before had been ignored. Garment workers were ordered to return the following day and the building collapsed during the morning rush-hour.
Following this devastating collapse an independent legally binding agreement (The Accord) was designed to make all garment factories in Bangladesh safe workplaces. To date this Accord has been signed by over 150 apparel corporations from 20 countries worldwide. Arup was approached to conduct 1,500 structural surveys with Arup Ireland leading the project.
Main Objective
The objective of the project was to help ensure that there was no repeat of the Rana Plaza collapse. Arup developed a methodology that:
1. Classified the buildings according to perceived risk of structural failure,
2. Gave recommendations as to immediate and longer term actions to be implemented in the factories to reduce the risk, and
3. Could be applied to a large number of buildings over a short period of time.
The inspectors used Arup Inspect, an iPad App developed by Arup, to record on-site information. The app allows users to develop project specific templates while spatially recording photos and observations on building plans, documents or images. All the information was spatial recorded in GIS to allow for categorisation of areas and factories.
Typical Screenshot of Arup Inspect
Arup’s methodology has been adopted nationally in the country’s 5000+ factories and will also be applied in other developing countries such as India and Cambodia with similar building control and safety concerns. The project was also nominated as one of the Engineers Ireland Projects of the Year for 2014.
One of the first aspects of this project was a study into the ground conditions and geology of the capital Dhaka.
Geology of Dhaka, Bangladesh
Bangladesh is one of the world’s largest deltaic countries and is formed at the confluence of the Brahmaputra, Ganges and Meghna rivers. More than 85% of the landmass is flat alluvial floodplains, criss-crossed by the rivers and their numerous tributaries, with the exception of slightly elevated uplands in the central and north-western parts of the country.
Dhaka is situated in the central part of the country at the southern tip of the Madhupur Tract, an area of recent uplift, dating back to the Pleistocene age. The tract is surrounded by the new and old floodplains of the Brahmaputra to the west and east respectively and the Ganges to the south. These floodplains are still experiencing high rates of sediment transport from the Himalayas during monsoon season, continually adding to the Holocene fluvial deposits.
The elevated tract consists of older sediments hosting the major parts of Dhaka and is surrounded by very recent alluvial and estuarine sediments. The older sediment sequence consists of fine sand of the Dupi Tila Formation overlain by stiff clay classified as Madhupur Clay.
Ground Conditions
Within Dhaka, investigations showed a firm to stiff overconsolidated silty clay with a high plasticity and typical ranges of 5-20 SPT values, generally increasing with depth. This layer can vary in thickness from 6 – 12m. The clay layer is under lain by clean, on occasion silty, sand with SPT values greater than 25.
Reports from Narayanganj, southeast of Dhaka, show the geological change as we move away from the Madhupur Tract and into the floodplains of the Meghna River. Due to the fluvial deposits in this low-lying area, the recommendation of deep foundations was relatively unchanging. Investigations show silt content averaging around 70% and SPT value rarely rising above 10 for 12-15m below ground level.
Ground conditions are quite favourable in the central elevated areas of Dhaka. However, factors such as swelling clays in high areas, ground subsidence in depressions of saturated soils and the increase in soft clays along stream beds toward the eastern side of the city, create poor even hazardous ground conditions.
Ground in low-lying floodplains surrounding Dhaka is quite hazardous for building. To escalate the issue, reclamation of these areas using river bed material has been ongoing for some time. Loading from this fill will lead to settlement of the underlying soft soil. It’s also worth noting that these soft ground areas are highly susceptible to
liquefaction under dynamic loading, as Dhaka is set in Seismic Zone II.
Dhaka has a population density of 45,000 per square km within the city area, nearly 75 percent more dense than Hong Kong. With no proper waste disposal facilities available, waste is dumped on the roadsides and in open space. An estimated 60% of waste is left uncollected. Investigation logs on occasion showed 1.5-2m of municipal waste, with evidence suggesting that this material is being used as a reclamation material in soft ground areas in the west and east of the city.
Foundation inspections
As part of the initial assessment a review of the foundation drawings was undertaken. Comparisons between the foundations and recommendations in the ground investigation report were noted. Some typical issues included pile foundations advised but not installed. Sometimes the depth of the spread foundation were higher than specified.
The foundation type and nature was entered into the Arup Inspect app including any discrepancies between design and construction information. The data was uploaded to the risk assessment for the building. The final report issued to the owner was developed very quickly using the Arup Inspect app, including recommendations for further intrusive work, if necessary.
Cathal Mac an tSearraigh (Arup Ireland)
Canada House, St. Stephens Green, Dublin
Byrne Looby recently completed the detailed design of the embedded secant pile retaining wall to accommodate the 8m deep basement for this new office development at the corner of Dublin’s St. Stephens Green.
Basement Construction Underway
The city centre location, on the corner of
Earlsfort Terrace and St. Stephens Green,
required that our design meet tight
deflection constraints due to the site’s
close proximity to adjacent multi-storey
office buildings and neighbouring
properties. In addition due to the
restricted space available on site for the
proposed development, we were required
to limit our pile sizes wherever possible in
order to provide the largest basement
footprint achievable. As a result the pile
sizes varied between 900mm, 1200mm
and 1500mm diameter depending on the
installation location around the perimeter
of the basement.
The piles were installed by Murphy
International, using their powerful Bauer
BG 28 rotary rig. Extremely strong
limestone bedrock was encountered on
site, close to the proposed basement
formation level of 8.0m bgl, resulting in all
piles being socketed between 2 to 3m into
the underlying rock.
Due to the deflection constraints, a high
level propping system was required, with
the main contractor M.B. McNamara
Construction Ltd engaging Hegarty
Demolition to install a series of
Groundforce proprietary cross props to
restrain the pile wall at ground level.
The basement excavation is almost
complete, with the construction of the
basement slab and internal walls and
columns progressing.
The design services provided by Byrne
Looby, in conjunction with the flexibility in
pile sizes offered by Murphy International
and the powerful rock drilling capabilities,
ensured that a robust yet efficient
solution was provided.
High Level Propping System
Maurice Ryan (Byrne Looby Partners)
Open-faced Pipe Jacking beneath the
Royal Canal in Leixlip
In June this year, Newry-based Terra
Solutions Ltd. installed 60m of 1500mm
internal diameter wastewater pipeline by
pipe jacking under the Royal Canal and the
Dublin-Sligo railway line at Leixlip, Co.
Kildare. This crossing was part of the
North Leixlip Sewerage Scheme which was
designed by Tobin Consulting Engineers
on behalf of Irish Water.
Tunnelling Works Underway
The site investigation for the scheme
showed that the pipe jack alignment was
within strong to very strong Dinantian
Upper Impure Limestone, commonly
known as "Calp". Following examination
of the site investigation data, it was
decided to utilise an open-face pipe
jacking shield rather than the closed-faced
systems commonly employed for this type
of project. Observations of groundwater
levels and the condition of the bedrock
gave confidence that the pipe jack could
be completed without encountering
significant inflows of groundwater.
The successful operation of the open-face
pipe jacking shield allowed the project to
be completed in 9 days and with a
minimal site footprint and minimal
difficulties in disposing of the tunnelling
arisings, which were dry crushed
limestone.
The project showed that the use of more
traditional, non-automated, trenchless
construction techniques is still very
worthwhile given the correct ground
conditions and appropriately skilled
personnel.
Barry McAllister (Terra Solutions Ltd.)