civil pile presentation[1]...kasun
TRANSCRIPT
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!