Assignment 01- Construction

7/30/2019 Assignment 01- Construction

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Civil Engineering

Construction

Introduction

This report covers types of construction activities. First earth moving equipments used in

construction in foundation and sub structure are discussed. Then the report covers the

safety and productivity in deep excavation. The Ground water control methods and

temporary works used for stability are covered. Pile foundation techniques, drainage

work are also included and finally culverts and installing services are discussed.

Ideas have been generated based on creative thinking and evaluations of the methods

used and proposals for improvements are also included in the report in each sub section.

The report was completed by gathering information from ICBT Civil Engineering books,

Notes given by our Civil Engineering Construction A lecturer and Internet. This task has

given us a good knowledge about Civil Engineering Construction.

International College of Business Technology 1



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Construction

Problem overview:

ABC construction Ltd is planning to start a residential development project which

contains apartment buildings (four ten storey buildings), shopping complexes,

recreational areas. This project involves in constructing buildings, developing the road

network within the site, installing the services such as electricity, water, telephone, etc.

and developing the drainage network which direct waste water and sewage to water

treatment plant and storm water to nearby river. Natural stream line is flowing the throw

the proposed development site and designers decide not to interrupt the stream line,

because it will give good aesthetic appearance to the area after the development.

Soil investigation report reveals that proposed construction site consists of sandy soil, but

approximately 4m below the ground level there is a 5m thick clay layer. Bed rock is

about 13m below the ground level. Ground water table is at about 3m below the ground

level. Designers of the apartment building decided to use pile foundation.

ABC construction Ltd is about to start construction and they are planning earth work and

substructure activities. You are a technician working on ABC construction Ltd. Your

senior engineer asked you to carry out the following tasks.

a) Provide an overview of the types of heavy equipment must be used in this project

b) Describe the appropriate methods and resources to ensure the safety and the

productivity in deep excavation.

c) Define the types of temporary work required to deal with stability and ground water

problem.

d) Describe the techniques of installing piling system and detail method and process of

constructing pile foundation in this situation.




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e) Describe the methods and resources used in processes, undertaking drainage work

including culverts as well as installing services.

Site Plan:




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1) Earth moving equipments:

Earthmoving equipment is used in the construction industry to shift large amounts of

earth, dig foundations and landscape areas. Various equipment are used in earth moving

purposes such as excavators and backhoes and more. These are commonly being used by

contractors for various construction projects where large amounts of materials, earth and

other items must be moved. The hydraulic earthmoving equipments are designed

carefully to enhance operating efficiency as well as safety. These powerful and high

performance equipments are suited for tough jobs.

ABC Construction Ltd is going to start a residential development project which contains

apartment buildings, shopping complexes, recreational areas. The project involves the

following necessities;

• Construction of buildings which needs pile foundation.

• Developing the road network within the site.

• Installing the services such as electricity, water, telephone etc.

• Developing the drainage network which direct waste water and sewage to water

treatment plant.

• Storm water to nearby water.

The selection, management and maintenance of construction plant are particularly

important when considered in the context of earth moving and excavation plant. The site

conditions and the volume of work entailed will be considered when deciding to use

which form of plant and equipments to use so that it will be an economical venture. The

difference between plant which is classified as earth moving equipment and excavating

machines is narrow since a piece of plant which is designed primarily to excavate will

also be capable of moving the soil to an attendant transporting vehicle and likewise




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machines basically designed to move loose earth will also be capable of carrying out to

some degree of excavation works.

A drawing should be produced indicating the areas and volumes of cut and fill required

before any earth moving work is started to enable a programme to reduce machine

movements to a minimum. For each construction activity different types of machinery

and equipment is needed. A small overview for each activity will be done and type of

machinery required will be discussed.

1. Construction of building (pile foundation):The designers of the apartment building have decided to use pile foundation for the

construction of the building. So to dig holes called bore holes to put the piles into the

ground and up to the bed rock a machine called a drilling rig has to be used.

2. Developing the road network within the site:

The project does not involve major roads or motorways but it involves in developing a

road network within the site. This will include removing topsoil, scraping and grading

the exposed surface to the required formation level. Scrapers and rollers are some of

the machinery used in this regard.

3. Installing the services such as electricity, water, telephone etc:

In planning the layout of these services it is essential that there is adequate

coordination between the various undertakings and bodies concerned if a logical and

economical plan and installation programme is to be formulated. Most services are laid

under the footpath or verge so that repairs will cause the minimum of disturbance.

Services which can be grouped together are often laid in a common trench

commencing with the laying of the lowest service and backfilling until the next service

depth is reached and then repeating the procedure until all the required services have

been laid. For this purpose trenchers and backhoe machinery can be used.




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4. Developing the drainage network:

Traditional method of constructing a drainage is to simply dig a trench to the correct

depth and fall, lay the pipes by hand on gravel, 150 mm clear of the bottom

surrounding them with gravel by hand and then backfill by machine.

The excavation of the trench must be carried out accurately and safely. Trenchers can

be used to excavate the trench.

5. Excavation:

For the purpose of excavation bull dozers, backhoe, scrapers, excavators and many

other equipments will be used.

According to the project requirements the following types of earthmoving equipment and

machinery are used in the project;

1. Bull dozer:

Bulldozers are large and heavy vehicles making them a good

choice for demolition and clearing sites. Caterpillar tracks give

bulldozers a distinct advantage allowing them to be

surprisingly maneuverable for their extreme weight. The tracks

have strong grips helping them to tackle uneven terrain. The

tracks are also quite wide which helps to distribute their heavy

weight preventing them from sinking in sandy or muddy ground.

Bulldozers are renowned for holding their ground which gives them phenomenal

strength for pushing and dragging obstructions in their path. Some models of tanks

can even tow up to 70 tons of weight and are used for moving written off vehicles and

military purposes as well as in construction and demolition projects.

The bulldozers main strength is clearly its weight. Using this weight and its two fitted

blades bulldozers are capable of performing a variety of tasks. The two component

blades are the dozer and the ripper.




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The Dozer blade is fitted to the front of the bulldozer and is the main drive for

clearing obstacles. The dozer is made from a piece of heavy weight metal plate which

is extremely durable. The dozer is also used for moving mounds of earth, sand and

general debris.

The Ripper blade is a long blade attached to the back of the bulldozer and (as the

name suggests) is useful for ripping and breaking up obstructions. Rippers resemble a

claw and are available in different designs for different purposes. A single ripper

blade is called a shank and provides good leverage for heavy ripping jobs. Shanks can

be arranged in groups of two or more to provide more grip for spread out or scattered

obstructions and debris.

2. Excavators

Excavators are used to excavate large quantities of earth and for other jobs on

construction sites. Excavators can do the manual work of ten or twenty people in

much less time by one person alone.

Excavators have been in use since the nineteen thirties and ever since are a staple site

on almost all construction sites. Whatever you are aiming to do on your construction

site there's an excavator or combination of excavators that can help you to achieve it.

Excavators are available in many different designs for different jobs. To help you find

the right solution for your job we've provided a quick low down of some of the

excavators available. There are two types of excavators dragline excavators and long

reach excavators.

For this project a dragline excavator is used as this machine is used for bulk

excavation and this machine is also used for excavating in loose and soft soils.

Dragline Excavators

Dragline excavators are used on site for excavating earth. Unlike

other excavators which rely on the strength of the arm to excavate




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earth dragline excavators use pressure applied through a cable to literally drag earth

from the ground.

Dragline extractors come in different sizes for different jobs. Large draglineexcavators are mainly used in surface mining amongst other operations whilst the

smaller ones are used for civil engineering jobs such as road works and road

construction.

The dragline excavator functions by using a large bucket which is suspended form a

large truss. Using cables and chains the bucket can be controlled to a high degree of

accuracy. Different ropes are used to control the horizontal and vertical movements

which can take a little time to get used to. The accuracy to which a dragline can

excavate depends on upon the skill of the operator.

3. Dump trucks

Dump truck is a term broadly used to describe two different vehicles which are used

on construction sites. Dumpers are small, one man vehicles used to carry loads of

building supplies and waste to and from sites. Dump trucks are much larger vehicles

which are used for transporting building materials to construction sites.

Advantages of Using Dump Trucks

Dump trucks are useful for transporting large loads of loose building materials on and

off site such as gravel, earth or sand. Dump trucks are instantly recognisable by the

large box shaped container positioned at the back of the truck.

The container can be raised and lowered by hydraulics so that loads of aggregate can

be dumped easily without having to be manually dug out of the container. The back

door of the box is on hinges so as the weight of the material tips against the door it

props open allowing for a controllable flow of its contents.

Different Kinds of Dump Trucks




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Dump trucks are available in a variety of different specifications for different roles in

construction and building supply. Here is a rundown of some of the most commonly

used dump trucks on site.

• Standard dump trucks have an appearance similar to a normal

truck. This is as they are modelled on a full length truck chassis

with the hydraulically operated dump box on the back. The

leverage of the box is controlled by a hydraulic mechanism

which is located between the cab of the truck and the dumping

box at the back.

• Articulated dump trucks are different to other kinds of dump trucks as the cab

is fixed to the truck and is irremovable. Articulated dump trucks are steered

using hydraulic rams that pivot the cab on a point as opposed to steering using

the front axle.

• Transfer dump truck is a name given to a dump truck which tows a detachable

trailer used for storing aggregate. The trailer is used as a container and is

powered by an electric motor. Rollers are used to transfer aggregate from the

trailer to the dump truck.

For this project an articulated dump truck is used because it has increased handling

which over rough and uneven grounds giving a clear advantage on undeveloped sites.

4. Dumpers

Dump truck is a term broadly used to describe two different vehicles which are used

on construction sites. Dumpers are small, one man vehicles used to carry loads of

building supplies and waste to and from sites. Dump trucks are much larger vehicles

which are used for transporting building materials to construction sites.

Modern dumper models are usually diesel powered and steer from the

middle of the vehicle using an articulating chassis to "pivot" steer.




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Dumpers are used to haul building materials and loads of earth and other waste

materials to be taken off size.

As well as being diesel driven dumpers are also fitted with electric controls to power

the hydraulically powered skip. These alternative power sources offer more

maneuverability but usually cost more and require more regular maintenance to keep

them functioning.

Other advances in modern dumpers include roll frames designed to protect the driver

if the dumper tips. As well as roll frames falling object frames are also available to protect drivers from any unexpected drops.

Other advancements mainly focus on improving the power of the dumpers skip.

Models with power assisted tipping are available which lift the skip as they tip. Other

popular developments include swivel skips which rotate to prevent tipping sideways.

These became popular for construction sites with little space for maneuvering such as

roadside sites.

A popular addition is a tow hook attached to the back of the dumper. This has proven

practical for towing power sources such as air compressors and generators on and off

site. Other modifications have been designed for specific jobs to complete tasks on

site.

5. Scrapers:

This piece of plant consists of a power unit and a scraper bowl and is used to excavate

and transport soil where surface stripping, site leveling and cut and fill activities are


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Civil Engineering

Construction

planned, particularly where large volumes are involved. These machines are capable of

producing a very smooth and accurate formation level.

6. Rollers:

Roller is a term used to describe a range of machines used to flatten and compress

different surfaces. Rollers are commonly referred to as steam rollers however steam is

rarely used to power modern models. Similar to bulldozers, rollers rely on brute

strength and are invaluable for jobs involving levelling uneven or newly applied

surfaces.

Uses of rollers

A roller as a name is used to describe steam rollers as well as rollers used in agricultural

and other purposes. Many people still refer to road rollers as steam rollers even though

very few rollers are actually powered by steam. Usually only large scale rollers used for

jobs such as road work are powered by steam.

Road rollers are also known as roller compacters. This is as the roller

functions by compacting loose surfaces of soil, gravel, concrete and

other materials. This process is commonly used for creating roads and

laying foundations.

Using the weight of the entire machine the loose materials are

compressed together to form a tough, even surface. The first stage is

carried out using a roller with pneumatic tyres where the usual roller is

replaced by two rows of pneumatic tyres. The two rolls are fitted to the

front and back and the flexible nature helps the roller to form the ground. The surface is

then completed using a metal drum to give shape.

Variations




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Rollers, like many other industrial tools, can easily be adapted to complete a range of

tasks. Roller designs range from hand operated single drum devices to rollers fitted with a

cab weighing up to 20 tons.

• Rollers are often adapted for use on landfill sites to compact excess levels of

waste. By fitting a different set of wheels with a more uneven texture the excess

waste can be compacted down into a smaller space.

• Many new rollers have modified hollowed drums. Using this system the roller can

be easily transported on site and filled with water to add weight. Once the work

has been completed the water can be drained allowing for easy transportation

back off site.

• Another economical variation is to have vibrating drums. For certain jobs this can

be useful as the motion of the drum exerts more pressure without the need for

extra weight.

Traditional designs and hand driven models often feature a single drum. Rollers are

available with two or more drums to reduce repeat runs over surfaces. Other designs have

featured a single drum with back rollers replaced with pneumatic tyres. Using tyres

instead of drums can improve grip significantly.

7. Backhoe:

Backhoe loaders are one of the most useful multi-purpose pieces of machinery

available today for construction workers, farmers and other contractors. Even though

other tools can be used to accomplish many of the tasks that backhoes are used for, a

lot of people prefer to work with a backhoe. They're compact and they consolidate the

tools used for separate jobs into one unit.


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Civil Engineering

Construction

Backhoe loaders are very common and can be used for a wide variety of tasks:

construction, small demolitions, light transportation of building materials, powering

building equipment, digging holes/excavating, landscaping

Their relatively small frame and precise control make backhoe-loaders very useful and

common in urban engineering projects such as construction and repairs in areas too small

for larger equipment. Their versatility and compact size makes them one of the most

popular urban construction vehicles. For larger projects, a tracked excavator is generally

used.

8. Front loader:

Front loader is a type of tractor, usually wheeled, sometimes on tracks, that has a front

mounted square wide bucket connected to the end of two booms (arms) to scoop up

loose material from the ground, such as dirt, sand or gravel, and move it from one

place to another without pushing the material across the ground. A loader is commonly

used to move a stockpiled material from ground level and deposit it into an awaiting

dump truck or into an open trench excavation.

Loaders are used mainly for uploading materials into trucks, laying pipe, clearing

rubble, and digging. A loader is not the most efficient machine for digging as it cannot

dig very deep below the level of its wheels, like a backhoe can.

9. Piling Rig:


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Piling rig is a machine which creates holes (usually called boreholes) and/or

shafts in the ground. Piling rig uses a helical screw which is driven into the ground with

rotation; and the earth is lifted up the borehole by the blade of the screw. This machine is

used to bore holes into the earth until the bedrock so that piles can be installed into it so

that a pile foundation can be done.

10. Trenchers;

These are machines designed to excavate trenches of constant width with

considerable accuracy and speed. Most trenches work on a conveyor principle having

a series of small cutting buckets attached to two endless chains which are supported

by a boom that is lowered into the ground to the required depth.

The spoil is transferred to a cross conveyor to deposit the spoil alongside the trench

being dug, or alternatively it is deposited onto plough shaped deflection plates which

direct the spoil into continuous heaps on both sides of the trench being excavated as

the machine digs along the proposed trench run.




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2) Safety and productivity in deep excavation:

Deep excavation is one where an excavation in soil or rock is typically done for morethan 4.5 m. Deep excavation requires careful design and planning. Retaining and support

system selection in deep excavation can have significant impact on time, cost and

performance.

ABC Construction Ltd designers have proposed piled foundation for its ten storied

buildings so deep excavation on large scale won’t be necessary for the construction of

building. A drilling rig will be used to drill down to the bed rock. Pile sockets have to be

installed, but for this only maximum of 1m-2m has to be excavated so this wouldn’t be a

deep excavation.

Construction of the road network, drainage network, and other services such as

electricity, water and etc have to be done, but for these purposes a maximum of 1m-2m of

excavation would be well suited and as its sandy soil for 4m its not going to a deep

excavation for these constructions.

Deep excavation will be done only for the construction of water treatment plant. During

which ground water control has to be done as well. Cave-ins pose the greatest risk and

are much more likely than other excavation related accidents to result in worker fatalities.

Other potential hazards include falls, falling loads, hazardous atmospheres, and incidents

involving mobile equipment.




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The general rules that have to be followed during deep excavations are as follows,

• Keep heavy equipment away from trench edges.

• Keep surcharge loads at least 2 feet (0.6 meters) from trench edges.

• Know where underground utilities are located.

• Test for low oxygen, hazardous fumes and toxic gases.

• Inspect trenches at the start of each shift.

• Inspect trenches following a rainstorm.

• Do not work under raised loads.

There are different types of protective systems used during deep excavation. Designing a

protective system can be complex because many factors have to be considered such as

soil classification, depth of cut, water content of soil, changes due to weather or climate,

surcharge loads and other operations in the vicinity.

The main components of retaining systems are as follows.

• Sloping involves cutting back the trench wall at an angle inclined away from the

excavation.

• Shoring requires installing aluminum hydraulic or other types of supports to

prevent soil movement and cave-ins.

• Shielding protects workers by using trench boxes or other types of supports to

prevent soil cave-ins.




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Conclusion:

During deep excavations it’s necessary to safeguard all workers in the site. Necessary

personal protective equipments will be given to workers according to their job roles.

Fencing and other safety measures will be taken into account when doing deep

excavation. Proper training should be given to all workers at the site. ABC Constructions

has its own safety policies which will be upheld by all its employees during work and in

site.

Proper Training and safety measures will give a really good moral boost to all the

employees as a safe working environment is essential for any kind of construction work.

When the moral of the employees is high performance of each employee increases and

thus productivity will increase rapidly and ensure the companies profitability.

Proper supervision will be done at all times and appropriate supervisors and managers

will ensure that supervision is done for all the works that are implemented in the site. Site




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inspections will be done on regular basis to look into the welfare and safety of the

employees.

Welfare facilities will also be considered to give a moral booster for the workers. Proper

machinery will also be used for the appropriate works so that work is done quickly and

efficiently, And thus ABC Construction Ltd achieves its goal on safety and productivity.

3) Temporary work to deal with stability and ground water problem:

Ground water can be defined as water which is held temporarily in the soil above the

level of the water table. Below the water table level is the subsoil water which is the

result of the natural absorption by subsoil’s of the ground water.

The fundamental requirement of ground water control measures is that they should ensure

stable and workable conditions throughout, so that excavation and construction can take

place economically and under safe conditions at all times. The concept of effective stress

is fundamental to understanding the inter relationship between groundwater and soil

strength and stability.

The stability and bearing capacity of a subsoil will depend upon the physical

characteristics of the soil and in particular upon the particle size which ranges from the

very fine particles of clay soils to the larger particles of some granular soils.




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The voids caused by excavation works encourage water to flow since the opposition to

the ground water movement provided by the soil has been removed. To maintain the

stability of the soil the flow of water has to be restricted by geotechnical processes. There

are two main methods in which ground water and stability can be achieved.

1) Temporary exclusion of ground water.

2) Permanent exclusion of ground water.

Temporary exclusion of ground water:

There are five types of temporary exclusion of ground water. They are as follows,

1. Sump pumping;• Suitable for gravels and coarse sands when working in open shallow excavations.

• The sump should be excavated below the formation level of the excavation.

• Small ditch is cuts around the excavation, falling towards the sump.

Disadvantages:

•

Water flows towards the excavation – risk of collapsing the sides.

• Pumping depth Is limited to 7.5 m – limitation in suction lift

• Standby pumps must be available to continue pumping

2. Well point systems;

• Popular methods of water lowering in non-cohesive soils up to a depth of 5m –

6m.

•Installing number of filter wells about 50mm dia. And 0.5 m to 1m long, around

the excavation.

• To dewater an area beyond this depth requires multistage installation.

• Stand by pump is required.

• This will help to keep system in full operation.




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• This will prevent collapse of excavation at pump failure.

3. Bored well pumping;

• Use surface pumps with suction pipes installed in bored wells.

• Suitable for sandy and gravel soil.

• Principle is same as well point system

• Running cost is low.

4. Horizontal ground water control

• Above mentioned systems are vertical systems.

• 100mm diameter perforate PVC suction pipe is installed in ground.

• Covers with nylon filter to prevent fine particles.

• Pipes are installed using special machines.

5. Electro – osmosis;

• Uncommon and costly method.

•

Used to dewater cohesive soil.• Soil particles are negatively charged.

• Positive molecules water particles are attached to them

• Two electrodes are inserted in to the ground and electric charge is passed between

them.

• Well point will be cathode.

• Water will flow to cathode..

Permanent exclusion of ground water:

1. Soldier pile walls:

Soldier pile and lagging walls are some of the oldest forms of retaining systems used in

deep excavations. These walls have successfully being used since the late 18th century




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in metropolitan cities like New York, Berlin, and London. The method is also

commonly known as the "Berlin Wall" when steel piles and timber lagging is used.

Alternatively, caissons, circular pipes, or concrete piles can also be used as soldier

piles but at an increased cost. Timber lagging is typically used although reinforced

concrete panels can be also utilized for permanent conditions. Soldier pile walls are

formed by:

1. Constructing soldier piles at regular intervals (6 ft to 12 ft, typical)

2. Excavating in small stages and installing lagging.

3. Backfilling and compacting the void space behind the lagging.

Moment resistance in soldier pile and lagging walls is provided solely by the soldier

piles. Passive soil resistance is obtained by embedding the soldier piles beneath the

excavation grade. The lagging bridges and retains soil across piles and transfers the

lateral load to the soldier pile system

2. Sheet piles;

Sheet pile walls are constructed by driving prefabricated sections into the ground. Soil

conditions may allow for the sections to be vibrated into ground instead of it being

hammer driven. The full wall is formed by connecting the joints of adjacent sheet pile

sections in sequential installation. Sheet pile walls provide structural resistance by

utilizing the full section. Steel sheet piles are most commonly used in deep

excavations, although reinforced concrete sheet piles have also being used

successfully.

Steel sheet piling is the most common because of several advantages over other

materials:




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1. Provides high resistance to driving stresses.

2. Light weight

3. Can be reused in several projects.

4. Long service life above or below water with modest protection.

5. Easy to adapt the pile length by either welding or bolting

6. Joints are less apt to deform during driving.

Sheet pile walls are constructed by:

1. Laying out a sequence of sheet pile sections, and ensuring that it will interlock.

2. Driving (or vibrating) the individual sheet piles to the desired depth.

3. Driving the 2nd sheet pile with the interlocks between the 1

st

pile and 2nd "locked"4. Repeating steps 2 & 3 until the wall perimeter is completed

5. Use connector elements when more complex shapes are used.

Sheet pile wall disadvantages are:

1. Sections can rarely be used as part of the permanent structure.

2. Installation of piles is difficult in soils with boulders or cobbles. In such cases, the

desired wall depths may not be reached.

3. Excavation shapes are dictated by the sheet pile section and interlocking elements.

4. Sheet pile driving may cause neighborhood disturbance

5. Settlements in adjacent properties may take place due to installation vibrations

3. Diaphragm wall;

• It’s a method used for permanent exclusion of ground water as well as excavation

support.

• Suitable for all types of soil.

• Cast in ground up to 30m and width 0.45 m to 1m.

• Usually in-situ reinforced concrete installed using the bentonite slurry method.

• It has the advantages of low installation noise and vibration.




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• Can be used in restricted spaces.

Applications of diaphragm wall

1. Earth retention walls for deep excavations, basements, and tunnels.

2. High capacity vertical foundation elements.

3. Retaining wall-foundations

4. Retaining wall-water control.

5. Used in top-down construction method as permanent basement walls

4. Slurry Trench cut off;

•There are non structural thin cast in situ un reinforced diaphragm walls.

• Suitable for sub soils of silts, sands and gravels.

• Used only as a water barrier, not to support soil.

• Must be used with conjunction with earth support or battered excavaton.

Applications of Slurry trench cut off;

1. Water and seepage control for deep excavations.

2. Cut-off curtains.

3. Contaminated groundwater / seepage control

4. Gas barriers for landfills

Conclusion:

From the above mentioned temporary ground water systems the well point system is the

best system for this project. As ground water control will be done for the water treatment

plant, the excavation will not go beyond 5-6 m.

The sump pumping method will not be used in this project because the water might flow

towards the excavation and there is a risk of the sides collapsing. Bored wells is not

necessary as the excavation depth is not going to be more than 6m. so the best way to

deal with stability and ground water control is to use the well point system.




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Permanent exclusion of ground water wouldn’t be needed for this project. If needed then

sheet piling is the best method. Sheet piling maybe used in the water treatment plant to

ensure a safe passage for the workers.

A temporary work such as cofferdam is also required to build a culvert across the stream

line. A cofferdam will be built on one side of the stream line and then after concreting is

done on that side, the cofferdam is moved to the next side and then it too will be

concreted and then the slab will be installed for the culvert.

4) Pile foundation:

Pile foundations are the part of a structure used to carry and transfer the load of the

structure to the bearing ground located at some depth below ground surface. The main

components of the foundation are the pile cap and the piles. Piles are long and slender

members which transfer the load to deeper soil or rock of high bearing capacity

avoiding shallow soil of low bearing capacity.

Classification of piles

• End bearing piles (point bearing piles)

• Friction piles (cohesion piles )




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• Combination of friction and cohesion piles

Classification of pile with respect to type of material

•

Timber • Concrete

• Steel

• Composite piles

Classification of pile with respect to effect on the soil

• Driven piles;

Driven piles are considered to be displacement piles. In the process of driving the

pile into the ground, soil is moved radially as the pile shaft enters the ground.

There may also be a component of movement of the soil in the vertical direction.

• Bored piles;

Bored piles (Replacement piles ) are generally considered to be non-displacement

piles a void is formed by boring or excavation before piles is produced. Piles can

be produced by casting concrete in the void. Some soils such as stiff clays are

particularly amenable to the formation of piles in this way, since the bore hole

walls do not requires temporary support except cloth to the ground surface.

Advantages and disadvantages of different pile material

Wood piles

+ The piles are easy to handle

+ Relatively inexpensive where timber is plentiful.

+ Sections can be joined together and excess length easily removed.

-- The piles will rot above the ground water level. Have a limited bearing capacity.

-- Can easily be damaged during driving by stones and boulders.

-- The piles are difficult to splice and are attacked by marine borers in salt water.




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Prefabricated concrete piles (reinforced) and pre stressed concrete piles. (driven)

affected by the ground water conditions.

+ Do not corrode or rot.

+ Are easy to splice and relatively inexpensive.

+ The quality of the concrete can be checked before driving.

+ Stable in squeezing ground, for example, soft clays, silts and peats pile material can be

inspected before piling.

+ Can be re driven if affected by ground heave. Construction procedure is unaffected by

ground water.

+ Can be driven in long lengths.

+ Can increase the relative density of a granular founding stratum.-- Relatively difficult to cut.

-- Displacement, heave, and disturbance of the soil during driving.

-- Can be damaged during driving. Replacement piles may be required.

-- Sometimes problems with noise and vibration.

-- Cannot be driven with very large diameters or in condition of limited headroom.

Driven and cast-in-place concrete piles

+ Can be inspected before casting can easily be cut or extended to the desired length.

+ Relatively inexpensive.

+ Low noise level.

+ The piles can be cast before excavation.

+ Pile lengths are readily adjustable.

+ An enlarged base can be formed which can increase the relative density of a granular

founding stratum leading to much higher end bearing capacity.

+ Reinforcement is not determined by the effects of handling or driving stresses.




Civil Engineering

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+ Can be driven with closed end so excluding the effects of GW

-- Heave of neighboring ground surface, which could lead to re consolidation and the

development of negative skin friction forces on piles.

-- Displacement of nearby retaining walls. Lifting of previously driven piles, where the

penetration at the toe has been sufficient to resist upward movements.

-- Tensile damage to unreinforced piles or piles consisting of green concrete, where

forces at the toe have been sufficient to resist upward movements.

-- Light steel section or precast concrete shells may be damaged or distorted by hard

driving.

-- Limitation in length owing to lifting forces required to withdraw casing, nose vibration

and ground displacement may a nuisance or may damage adjacent structures.-- Cannot be driven where headroom is limited.

-- Relatively expensive.

-- Time consuming.

-- Limited length.

Bored and cast in -place (non -displacement piles)

+ Length can be readily varied to suit varying ground conditions.

+ Soil removed in boring can be inspected and if necessary sampled or in- situ test made.

+ Can be installed in very large diameters.

+ End enlargement up to two or three diameters are possible in clays.

+ Material of piles is not dependent on handling or driving conditions.

+ Can be installed in very long lengths.

+ Can be installed with out appreciable noise or vibrations.

+ Can be installed in conditions of very low headroom.

+ No risk of ground heaves.

-- Concrete is not placed under ideal conditions and cannot be subsequently inspected.

-- Water under artesian pressure may pipe up pile shaft washing out cement.

-- Enlarged ends cannot be formed in cohesion less materials without special techniques.

-- Boring methods may loosen sandy or gravely soils requiring base grouting to achieve

economical base resistance.




Civil Engineering

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-- Sinking piles may cause loss of ground I cohesion-less leading to settlement of

adjacent structures.

Steel piles (Rolled steel section)

+ The piles are easy to handle and can easily be cut to desired length.

+ Can be driven through dense layers. The lateral displacement of the soil during driving

is low (steel section H or I section piles) can be relatively easily spliced or bolted.

+ Can be driven hard and in very long lengths.

+ Can carry heavy loads.

+ Can be successfully anchored in sloping rock.+ Small displacement piles particularly useful if ground displacements and disturbance

critical.

-- The piles will corrode,

-- Will deviate relatively easy during driving.

-- Are relatively expensive

Pile installation methods;

The installation process and method of installations are equally important factors as of

the design process of pile foundations. There are two main types of pile installation

methods; installation by pile hammer and boring by mechanical auger.

Pile Hammer;

The following factors have to be taken in to consideration if installation is to be carried

out using pile-hammer:




Civil Engineering

Construction

• the size and the weight of the pile

• the driving resistance which has to be overcome to achieve the design penetration

• the available space and head room on the site

• the availability of cranes and

• The noise restrictions which may be in force in the locality.

Pile driving methods (displacement piles)

Methods of pile driving can be categorised as follows:

1. Dropping weight

2. Explosion3. Vibration

4. Jacking (restricted to micro-pilling)

5. Jetting

A hammer with approximately the weight of the pile is raised a suitable height in a guide

and released to strike the pile head. This is a simple form of hammer used in conjunction

with light frames and test piling, where it may be uneconomical to bring a steam boiler or

compressor on to a site to drive very limited number of piles.

There are two main types of drop hammers:

• Single-acting steam or compressed-air hammers

• Double-acting pile hammers

Diesel hammers

Also classified as single and double-acting, in operation, the diesel hammer employs a

ram which is raised by explosion at the base of a cylinder. Alternatively, in the case of

double-acting diesel hammer, a vacuum is created in a separate annular chamber as the

ram moves upward, and assists in the return of the ram, almost doubling the output of the




Civil Engineering

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hammer over the single-acting type. In favorable ground conditions, the diesel hammer

provide an efficient pile driving capacity, but they are not effective for all types of

ground.

Pile driving by vibrating

Vibratory hammers are usually electrically powered or hydraulically powered and

consists of contra-rotating eccentric masses within a housing attaching to the pile head.

The amplitude of the vibration is sufficient to break down the skin friction on the sides of

the pile. Vibratory methods are best suited to sandy or gravelly soil.

Jetting: to aid the penetration of piles in to sand or sandy gravel, water jetting may beemployed. However, the method has very limited effect in firm to stiff clays or any soil

containing much coarse gravel, cobbles, or boulders.

Boring methods :

Continuous Flight Auger (CFA)

An equipment comprises of a mobile base carrier fitted with a hollow-stemmed flight

auger which is rotated into the ground to required depth of pilling. To form the pile,

concrete is placed through the flight auger as it is withdrawn from the ground. The auger

is fitted with protective cap on the outlet at the base of the central tube and is rotated into

the ground by the top mounted rotary hydraulic motor which runs on a carrier attached to

the mast.




Civil Engineering

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On reaching the required depth, highly workable concrete is pumped through the hollow

stem of the auger, and under the pressure of the concrete the protective cap is detached.

While rotating the auger in the same direction as during the boring stage, the spoil is

expelled vertically as the auger is withdrawn and the pile is formed by filling with

concrete. In this process, it is important that rotation of the auger and flow of concrete is

matched that collapse of sides of the hole above concrete on lower flight of auger is

avoided. This may lead to voids in filled with soil in concrete

The method is especially effective on soft ground and enables to install a variety of bored

piles of various diameters that are able to penetrate a multitude of soil conditions. Still,

for successful operation of rotary auger the soil must be reasonably free of tree roots,

cobbles, and boulders, and it must be self-supporting.

Underreaming

A special feature of auger bored piles which is sometimes used to enable to exploit the

bearing capacity of suitable strata by providing an enlarged base. The soil has to be

capable of standing open unsupported to employ this technique. In its closed position, the

under reaming tool is fitted inside the straight section of a pile shaft, and then expanded

at the bottom of the pile to produce the under ream. Normally, after installation and

before concrete is casted, a man carrying cage is lowered and the shaft and the under

ream of the pile is inspected.

H.D.P

Continuous helical displacement piles: a short, hollow tapered steel former complete with

a larger diameter helical flange, the bullet head is fixed to a hallow drill pipe which is

connected to a high torque rotary head running up and down the mast of a special rig. A

hollow cylindrical steel shaft sealed at the lower end by a one-way valve and fitted with

triangular steel fins is pressed into the ground by a hydraulic ram. There are no

vibrations.




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Displaced soil is compacted in front and around the shaft. Once it reaches the a suitably

resistant stratum the shaft is rotated. The triangular fins either side of its leading edge

carve out a conical base cavity. At the same time concrete is pumped down the centre of

the shat and through the one-way valve. Rotation of the fins is calculated so that as soil is

pushed away from the pile base it is simultaneously replaced by in-flowing concrete.

Factors influencing choice of pile

• Location and type of structure

• Ground conditions

• Durability

• Cost

Conclusion:

ABC Construction Ltd has to consider the above factors and the types of piles available

in order to get maximum benefit for the company. During the excavation a casing was

used and at the end of the casing a one way door is installed so that all the mud and clay

soil can be extracted by the piling rig.

After studying and analyzing all the necessary data the Bored and cast in –place piles are

selected because they are the piles that are best suited for the project. The Bored and cast

in –place piles can be installed in very large diameters, as the buildings are heavy

structures and exerting large foundation loads, large-diameter bored piles are usually the

most economical. Jacked piles are suitable for underpinning existing structures.

These piles can be installed in very long lengths. And also end enlargement up to two or

three diameters is possible in clays. To install these piles boring method is used, firstly

bentonite is used to put into the excavated hole and then a tube is put in and the

reinforcement is put and then the concrete is poured from the top of the hole to get the

piled foundation. This process is repeated until the piles are all put in place according to

the design of the ABC Construction Ltd’s design specifications.


http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm#PILELOCATION

http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm#PILEGROUND

http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm#PILEDURABILITY

http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm#PILECOST

http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm#PILEGROUND

http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm#PILEDURABILITY

http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm#PILECOST

http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm#PILELOCATION



Civil Engineering

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5) Drainage Network, culverts and installing services;

Drainage work:

The designers of ABC Construction Ltd ill specify the diameter of the drain which has to

be constructed. The structural strength of the drain depends upon the following;

• The strength of the material it is made of

When considering the strength of the material from which the pipe is made

manufacturer’s advice has to be sought.

• Bedding and surround detail




Civil Engineering

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The specification of bedding arrangements and depth restrictions are specified by

the department of transport.

• Depth of drain and width of trench

Designers will specify the depth and width of the trench.

• Surface loading

Drainage construction:

Traditional methods of construction are to simply dig a trench to the correct depth and

fall, lay pipes by hand on gravel, 150mm clear of the bottom, surrounding them with

gravel by hand and then back fill by machine. The excavation of the trench must be

carried out accurately and safely.

Accuracy is achieved by profile boards or laser and safety is achieved with trench sheets.

The width of the trench is set by the width of the bucket of the machine, so the right

choice is essential. Trencher is most appropriate to do this kind of work.

Excavation won’t be deeper than 1.2m so support is not needed but if the designers had

specified a deeper excavation then support has to be provided against collapse. Support

can be achieved by timber shoring or trench shields or boxes. Trench boxes are the best

solution as its less expensive and the advantages of speed far outweigh the rest.

The line and level accuracy is achieved by using laser guidance. This significantly helps

to reduce pressure o time and money. After the line and level Is checked Back filling has

to be done and this has to be carried out with care to avoid disturbing the pipes and to

provide reliable compacted ground over the pipe. Each layer has to be compacted very

well with a vibrating plate compactor. Testing must be carried out to ensure that the

completed drainage system works correctly.




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At the proposed site the drainage network has to pass over the stream so a drainage line

has to go on the side of the culvert which has been erected to cross the stream line. The

drainage line has to end up at the water treatment plant. The storm water has to be

collected from the road drainage and directed to the stream line. The surface water is

encouraged to flow off the paved area by cross falls which must be designed with

sufficient gradient to cope with the volume of water likely to be encountered during a

heavy storm.

The run off storm water is directed towards the edge of the road where it is in turn

conveyed by gutters or drainage channel to discharge into road gullies and then into the

stream line

Culvert:

A culvert is a box, conduit or pipe of large cross-section usually used to convey

pedestrians, water (foul or surface) or services in general under a road, canal or some

other elevated construction. In the true principle of culvert construction, a void for the

pipe would be excavated and covered after the pipes were placed, thus differentiating the




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process from tunneling. In practice this may not always be convenient or cost-effective:

hence the preference for tunneling in some situations.

The cut and cover technique involves considerable excavation, with sides usually

temporarily restrain by interlocking sheet piles or steel trench sheeting. Ground water

controls may also be required, particularly if in-situ concrete is specified as the culvert

material.

Construction

• In-situ concrete;

•In-situ concrete based with precast concrete crown;

• Precast concrete.

Precast concrete box culverts

These have proved the most popular specification for culverts, with manufactures

producing them in a wide range of sizes from about 1.000,1.500 and 2.000 m to suit a

variety of applications. These includes subways, stream crossings, animal (badger)crossings, sewers and sea outfalls. They are not limited to horizontal use, and may also be

used as vertical access shafts. Concrete is normally from ordinary Portland cement.

State delivery and installation should be carefully planned to coordinate hire of suitable

plant and operatives. Following excavation, a bed or foundation must be prepared from

well compacted selected granules of about 225 mm total thickness .This is leveled to suit

the situation, or placed on a slight incline for drainage purposes. Projecting reinforcement

loops or purpose-made threaded sockets provide crane lifting gear attachments for the

box units. After placing and leveling the first unit, second and subsequent units are

lowered and positioned for jointing. Pre-primed spigot and socket rebated joints are fitted

with a mastic jointing strip or gasket-bonded to the socket. If preferred, and site

conditions permit, the joints may be sealed with waterproof cement and sand mortar.




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With the first unit restrained, second and subsequent units have their weight partially

supported with tensioners draw the spigots into opposing sockets to compress the jointing

material /gasket. Care must be taken to ensure that the joints remain clean, and that the

bedding granules are excluded during the process.

Accommodation of services

The services which may have to be accommodated under a paved area could include any

or all of the following:

1. Public or private sewers

2. Electrical supply cables

3. Water mains

4. Telephone cables

5. Television relay cables

In planning the layout of these services it is essential that there is adequate co-ordination

between the various undertakings and bodies concerned if a logical and economical plan

and installation programme is to be formulated.

Sewers are not generally grouped with other services and due to their lower flexibility are

given priority of position. They can be laid under the carriageway or under the footpath

or verge, the latter position creating less disturbance should repairs be necessary. The

specification as to the need for ducts, covers and access positions for any particular

service will be determined by the undertaking or broad concerned. Most service are laid

under the footpath or verge so that repairs will cause the minimum of disturbance and to

take advantage of the fact that the reinstatement of a footpath is usually cheaper and

easier than that of the carriageway.




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Services which can be grouped together are very often laid in a common trench

commencing with the laying of the lowest service and backfilling until the next service

depth is reached and then repeating the procedure until all the required services have been

laid. The selected granular backfilling materials should be placed in 200 to 250 mm well

compacted layers. All services should be kept at least 1.500 clear of tree trunks, any small

tree roots should be cut, square trimmed and tarred.

Reference

Book

Construction Technology, R, Chaudley, Longman Group 1977

Lecture notes




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Construction

Prepared by the lecturer

Websites

http://www.planthiresolutions.com

http://ezinearticles.com/?Benefits-Of-Using-A-Backhoe-Loader&id=915992

http://www.deepexcavation.com/retainingsystems.html

http://www.sbe.napier.ac.uk/projects/piledesign/guide/chapter1.htm

Assignment 01- Construction

Documents

Transcript of Assignment 01- Construction