WELCOME1

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Civil Engineering Construction I - BE 2103

B.Sc. (Hons) in Quantity Surveying

Level-II Semester II

Course Work

Piling ConstructionGroup 06

Department of Building Economics

Faculty of Architecture

University of Moratuwa

Student Name(s) Reg. No.

Digashini G.P. 092619DFernando P.G. 092626VFernando W.D.H 092413PGunasekara T.A.K.G. 092631GKrishna M. 092650MMadusanka H.G.V 092459KPournima S. 092437RWijewardana W.M.C 092700T

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Introduction

Pile is a form of deep foundation.

It facilitates the construction of buildings (specially high

rise) where existing soil conditions are not satisfactory.

Depending on the predominant bearing type:

End bearing piles

Friction piles

Factors affecting choice of piles:

Soil condition

Intended loading

Cost

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Details of the project

Project name – “Mehewara piyasa” (EPF Head

Office for Department of Labour)

Project type – 30 Storey building

Client – Department of Labour Sri Lanka

Consultant – Central Engineering

Consultancy Bureau

Piling Contractor – MTD Walkers & Sons

Company (Pvt) LTD

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Details of the project..

Location – Narahenpita

Project Cost - Rs. 7.5 Billion Pile Type – Cast Insitu

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Planning and Management

Intended period of piling – 6 months Why planning and management is

essential?Heavy machinery with high running costs/ hire charges

Involvement of special skilled labour

Inability to initiate most of other construction activities before completion of piling

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Planning and Management..

Tools used for planning and managing:- Sequence of piling Bar Chart Daily labourer progress sheets Daily progress board

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Sequence of PilingSite Investigation

Site Clearance

Preliminary Excavation

Piling

Earth Retaining Work

Basement Excavation

Pile cap Construction

Basement ConstructionCore

Construction

General Construct

ion

Daily Labourer Progress Sheet

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Preliminaries

Preliminary works are the activities that take place prior

to the actual construction is initiated.

General preliminaries:

Soil/Site Investigation

Temporary services

(water, electricity etc)

Site office, vehicles

Name boards

Accommodation for labourers

Safety measures

Storage

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Preliminaries..

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Preliminaries…

Site Layout

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Preliminaries…

Soil Investigation

This is required to find out the following data in order to

design the piles for given service loads.

Soil type

Sub soil condition

Depth till bed rock

Nature of bed rock

Level of ground water table

Soil tests were carried out by Geotechnical Engineering

Division of the National Building Research Organization

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Preliminaries…

Most of the data are gathered by bore hole tests.

Other laboratory tests:-

Standard Cone Penetration – To gather data

regarding soil bearing capacity, soil cohesive strength

and pore water pressure.

Geomechanical Test - To obtain shear strength

parameters of the soil.

Atterberg Limit Test – To find nature of fine grained

soil : Plastic limit, shrinkage limit, liquid limit etc.

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Preliminaries…

Findings of soil tests

Water table – 2.5m below EGL

Moisture Content – Less than 20%

Depth (below EGL)

Soil condition

0-6m Silty Sand

6-14m Layers of peat, organic silt, sandy clay and clayey sand

14-16m Highly weathered rock

Below 16m Biotite granitic gneiss bed rock

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Excavation & Earth Moving

This is performed to convert the existing ground

condition to the required depth, slope.

Proper compaction is done to avoid undue settlement.

Excavated soil is moved and disposed off site.

Top soil excavation

Excavation up to basement level

Excavation for pile caps

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Earth Work Support System & Dewatering

Earth Work Support System:-

To prevent collapse of soil when excavating/boring

Ordinary timber/steel earth work supports maybe

used for typical excavations.

Bored holes walls cannot be effectively supported in

the same manner and is not practical.

Methods used:-

Slurry method for soil retaining

Casings for retaining

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Earth Work Support System & Dewatering..

Bentonite Slurry Method

This liquid is poured along simultaneously with drilling.

It forms an impermeable skin along its contact surface

thus preventing soil from falling in.

Provides additional benefit of cooling the drilling

equipment.

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Earth Work Support System & Dewatering..

Steel casings for soil

retaining:-

Soil close to ground level are

looser than deeper layers.

Bentonite is not able to hold such

loose soil.

Steel casings are cylinders which

are driven concentrically to the

piles to a depth about 8m.

21 PILING PROCESS

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Piling Details

According to soil investigation reports and design

loads of the building, the following pile types

were selected.Pile Type No of

piles

Bearing

Capacity of the

pile

Shear links

(High Yield)

details

Steel bar

(High Yield)

details

600 mm 13 1400 kN 10mm dia –

200c/c

8nr 20mm

dia

1500 mm 16 9000 kN 10mm dia –

200c/c

30nr 25mm

dia

1800 mm 84 12500 kN 10mm dia –

200c/c

26nr 32mm

dia

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Equipment & Machinery

Surveying instruments: Theodolite, Level

Drilling rig: Rotary drill rig

Drill bits: Augre, Cleaning bucket

Crane

Concrete pump

Shovel

Tremie pipes, funnels

De-sander

Welding machines

Back hoe, excavator

Trucks

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Piling procedure

1) Site clearance

This includes removal of trees, vegetation, top soil

and also required leveling and excavations.

2) Setting out

A licensed surveyor surveys and sets out the pile

locations.

Steel bars are used to identify and mark the

positions.

Pile layout is drawn using gathered data.

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Piling procedure..

The following diagram illustrates some basic steps of

piling.

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Drilling

The rotary drill rig is used with changing drill bits.

Initially 2-3 m depth is dug using the auger bit.

Then the steel casing is driven to its depth.

From water table level onwards, bentonite is pumped along

all throughout the drilling activity.

Augre bit is fitted again and drilling is continued until bed

rock is reached.

Drill bit is changed in several intervals to cleaning bucket on

the way.

Drilling is completed after going 2m below the bed rock.

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Drilling..

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Reinforcement cage

The R/F cage is fabricated on site using R/F steel bars.

Shear bars are bent to be circular.

Circular concrete spacers are used to provide necessary

clear cover and also keep the cage in correct position.

The cage is lowered into the bore hole using a crane.

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Reinforcement cage..

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Concreting

Tremie pipes are fixed end to end and lowered to the

bore hole at the centre.

The hopper funnel is fitted on the top most pipe.

A Styrofoam ball with diameter equal to inner diameter

of the pipe is place at the top, as a ‘travelling plug’.(To

make sure smooth flow of concrete)

Mixed concrete is poured at a steady rate and the

bottom of the pipe is slightly lifted up (about 25cm).

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Concreting..

To De-sander

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Concreting..

Overflowing bentonite is cleaned and re used

after sending through a de-sander.

Steel casing is removed lifting up, when concrete

is sufficiently workable.

The top most portion of the pile is broken and

removed since it is mixed with dirt and soil.

Pile caps are made later on.

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Pile Testing

Pile testing is carried out :

To check for any deformations

To check for strength, integrity

Basic types of testing:

Static/Maintained Load Test (MLT)

Pile Integrity Test (PIT)

Pile Dynamic Analyzer Test (PDA)

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Pile Testing..

Maintained Load Test (MLT)

Used to determine the settlement

of piles under continuous static

loading.

Piles are loaded with Concrete

mass blocks to a load 1.5x the

intended working loads.

After unloading, the settlement of

the pile is measured accurately.

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Pile Testing..

Pile Integrity Test (PIT)

Used to determine uniformity of pile.

A progressive wave is generated and accelerometers set on

several places recognizes the return waves – This identifies

any differences.

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Pile Testing…

Pile Dynamic Analyzer (PDA)

Used to find out dynamic bearing

capacity of the piles.

A weight is dropped from a crane

(along a guide rail cage) on to the

pile .

Displacements are measured and

bearing capacities are checked.

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Cost Proposal (Summary)

Item Amount Rs

Total Preliminaries 5,537,200.00

Piling 600mm diameter 3,087,500.00

Piling 1500mm diameter 3,888,000.00

Piling 1800mm diameter 3,240,240.00

Rock socketing 10,340,000.00

Pile hacking 773,200.00

MLT, PIT,PDA tests Rate only

Sub Total 26,826,160.00

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Special Issues

The 2 main environmental concerns were vibration and

noise.

Since the pile site is adjacent to office buildings,

complaints were made regarding vibration due to drilling.

Vibration Impact Assessment was done by NBRO.

Sound level around the site is measured daily to check

that it falls within the allowed decibel level foe urban

areas.

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Comparison between other pile types

Type Advantages Disadvantages

Precast

Concrete

(driven)

•Better build quality.

•Complete testing before

application

•Large diameters not

possible

•Driving may damage

them.

•Not suitable for dense

soils.

•Driving is excessively

noisy

Steel

(driven)

•High load carrying

capacity

•Suitable for dense soils

•Expensive

•Prone to corrosion

Wooden •Cheaper

•Easier to handle

•Effective splicing not

possible

•Prone to damage

•Lower strength

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Conclusions

All highrise building construction is made possible due

to pile foiundation.

Piling is typically subcontracted to a specialist company.

The process involves a lot of machinery, skilled labour,

testing procedures etc.

Basically the preliminaries cost is high.

Proper planning and management is essential when

dealing with highly cost concerning equipment.

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Conclusions…

Choice of insitu concrete piles:

Larger diameter

Variable lengths

Less ground disturbance

Less noise, vibration

Environmental impact should be considered (excessive

noise/vibration)

Involves of a lot of third party institutes for testing

purposes.

43 THANK YOU!