pile installation methods_bhushan
TRANSCRIPT
-
7/28/2019 Pile Installation Methods_Bhushan
1/36
Methods of Construction of
Pile Foundations
-
7/28/2019 Pile Installation Methods_Bhushan
2/36
Outline of Presentation
1. Methods of installation of piles
a. Driven Piles
b. Bored Piles2. Case study:- Piling work at
Bandra - Worli sea link ( BWSL )
4/19/2013 2
-
7/28/2019 Pile Installation Methods_Bhushan
3/36
Methods of installation
The methods of installation of piles are mainly
divided into two types
1. Pile Driving:- In this method the pile (Precast
or cast in situ) is driven into ground by meansof automated pile driving machines.
2. Pile Boring:- In this method the pile (Mostly
Precast) is bored into ground by means of by
hand operated or automated augers.
4/19/2013 3
-
7/28/2019 Pile Installation Methods_Bhushan
4/36
a. Driven Piles
The piles types which are installed using pile
driving methods includes:-
Timber piles
Steel piles Precast concrete piles
Prestressed concrete piles
Cast-in-situ piles
4/19/2013 4
-
7/28/2019 Pile Installation Methods_Bhushan
5/36
a. Driven Piles
Driven piles are installed by means of a driving
hammer or a vibratory driver. The various types
hammer types includes:-
1. Drop hammer,
2. Steam or air hammer,
3. Diesel hammer
4. Hydraulic hammer.
Use of these hammer types are classified as
percussive piling, which is subject to the requirementsof Noise Control Ordinance (HKSARG, 1997).
The use of noisy diesel, pneumatic and steam
hammers for percussive piling is generally banned in
built-up areas surrounded by noise sensitive receivers4/19/2013 5
-
7/28/2019 Pile Installation Methods_Bhushan
6/36
a. Driven Piles
Driven Piles consists of assembly
1. Dolly,
2. helmet
3. packing or pile cushion
The purpose of the assembly is tocushion the pile from the hammer
blows and distribute dynamic stresses
evenly without allowing excessive
lateral movements during driving.
In addition, the life of the hammerwould be prolonged by reducing the
impact stress. Pile cushion
(or packing) is generally not
necessary for driving steel piles4/19/2013
6
-
7/28/2019 Pile Installation Methods_Bhushan
7/36
Drop hammers
A drop hammer (8 to 16 tonnes) is liftedon a rope by a winch and allowed to fall
by releasing the clutch on the drum.
The stroke is generally limited to about
1.2 m except for the case of 'hard
driving' into marble bedrock where
drops up to 3 m have been used inHong Kong.
The maximum permissible drop should
be related to the type of pile material.
The drawback to the use of this type of
hammer is the slow blow rate, thedifficulty in effectively controlling the
drop height, the relatively large
influence of the skill of the operator on
energy transfer, and the limit on the
weight that can be used from safety
considerations.4/19/2013 7
-
7/28/2019 Pile Installation Methods_Bhushan
8/36
Steam hammers
Steam or compressed airhammers are classified as
single-acting
double-acting
depending on whether the
hammer falls under gravity or is
being pushed down by a second
injection of propellant.
A chiselling action is produced
during driving as a result of thehigh blow rate. Some single-acting
steam hammers are very heavy,
with rams weighing 100 tonnes or
more.
4/19/2013 8
-
7/28/2019 Pile Installation Methods_Bhushan
9/36
Steam hammers
Single acting Hammer Double acting Hammer
4/19/2013 9
-
7/28/2019 Pile Installation Methods_Bhushan
10/36
Diesel Hammer
In a diesel hammer, the weightis lifted by fuel combustion. The
hammer can be either single-
acting or double-acting.
Due to the high noise level andpollutant exhaust gases
associated with diesel hammers,
the use of diesel hammers has
been phased out in populated
areas.
The ram weight of a diesel
hammer is generally less than a
drop hammer but the blow rate
is higher.4/19/2013 10
-
7/28/2019 Pile Installation Methods_Bhushan
11/36
Hydraulic hammer
A hydraulic hammer is lessnoisy and does not produce
polluting exhaust.
The ram of the hammer is
connected to a piston,
which is pushed upward anddownwards by hydraulic power.
Some complex models have
nitrogen charged accumulator
system, which stores significantenergy allowing a shortened
stroke and increased blow rate.
4/19/2013 11
-
7/28/2019 Pile Installation Methods_Bhushan
12/36
Hydraulic Hammer (contd)
As such, the kinetic energy of the hammer depends not
only on the height of the stroke but also the acceleration
due to the injection of hydraulic pressure.
Most new hydraulic hammers are equipped withelectronic sensors that directly measure the velocity of
the ram and calculate the kinetic energy just before
impact.
The energy transfer ratio of hydraulic hammers ranges
between 0.8 and 0.9
4/19/2013 12
-
7/28/2019 Pile Installation Methods_Bhushan
13/36
Vibratory hammers A vibratory driver consists of a static
weight together with a pair of contra-rotating eccentric weights such that the
vertical force components are additive.
The vibratory part is attached rigidly to
the pile head and the pulsating force
facilitates pile penetration under thesustained downward force.
The vibratory driver may be operated at
low frequencies, typically in the range of
20 to 40 Hz, or at high frequencies
around 100 Hz (i.e. 'resonance piledriving').
Vibratory drivers are not recommended
for precast or prestressed concrete piles
because of the high tensile stresses that
can be generated.4/19/2013 13
-
7/28/2019 Pile Installation Methods_Bhushan
14/36
b. Bored Piles
Bored piles are mostly formed by machineexcavation. Excavation of the pile bore may also
be carried out by hand-digging in the dry known
as hand-dug caissons . When constructed in water-bearing soils which
are not self-supporting, the pile bore will need to
be supported using steel casings, concrete rings
or drilling fluids such as bentonite slurry,polymer mud, etc.
4/19/2013 14
-
7/28/2019 Pile Installation Methods_Bhushan
15/36
Machine Dug Bored Piles
The Machine dug piles are mainly divided
into:-
a.Mini Piles
b.Socketed H-Piles
c.Continuous Flight Augur piles
d.Large dia. Bored Piles
4/19/2013 15
-
7/28/2019 Pile Installation Methods_Bhushan
16/36
Mini Piles
Mini-piles are in a range of 100 mm
to 400 mm in dia. and can be
constructed to a depth of 60 m
depth or more, but verticality
control becomes more difficult at
greater depths.
They can be used for sites with
difficult access or limited
headroom and for underpinning.
In general, they can overcome
large or numerous obstructions
in the ground.
A mini-pile usually has four 50 mm
diameter high yield steel bars and
has a load-carrying capacity of
about 1 375 kN.
4/19/2013 16
-
7/28/2019 Pile Installation Methods_Bhushan
17/36
Socketed H-piles
Socketed H-piles are formed by inserting asteel H-pile section into a pre bored hole in
rock. The hole should have a diameter
adequate to accommodate the steel section
plus any necessary cover for corrosionprotection.
Cover to the pile tip is generally
unnecessary and the H-pile section can be
placed directly on the rock surface of the prebored hole. The common size of the pre
bored hole is about 550 mm. The hole is
then filled with non-shrink cement grout.4/19/2013 17
-
7/28/2019 Pile Installation Methods_Bhushan
18/36
Socketed H-piles
4/19/2013 18
-
7/28/2019 Pile Installation Methods_Bhushan
19/36
Continuous flight auger piles
Sizes of CFA piles range from 300 mm to 700 mm indiameter and their lengths are generally less than 30 m.
Once concreted, reinforcement bars or a steel H-pile
section may be inserted to provide resistance to lateral
load or to increase the load-carrying capacity.
These piles can be installed with little noise and
vibration and are therefore suited for sites in urban
areas.
However, this type of piles cannot cope with boulders.
The lack of penetration under continuous rotation due toa hard layer or an obstruction can lead to soil fighting upthe auger causing ground loss and settlement.
4/19/2013 19
-
7/28/2019 Pile Installation Methods_Bhushan
20/36
Continuous flight auger piles
4/19/2013 20
-
7/28/2019 Pile Installation Methods_Bhushan
21/36
Continuous flight auger piles
4/19/2013 21
-
7/28/2019 Pile Installation Methods_Bhushan
22/36
Large Dia. Bored piles
Large-diameter bored piles are used to supportheavy column loads of tall buildings and
highways structures such as viaducts.
Typical sizes of these piles range from 1 m to 3
m, with lengths up to about 80 m and workingloads up to about 45 000 kN ( 4.5 Lakh tonnes ).
The working load can be increased by socketing
the piles into rock or providing a bell-out (bulb) at
pile base. The pile bore is supported bytemporary steel casings or drilling fluid, such as
bentonite slurry.
4/19/2013 22
-
7/28/2019 Pile Installation Methods_Bhushan
23/36
Large Dia. Bored piles
4/19/2013 23
-
7/28/2019 Pile Installation Methods_Bhushan
24/36
Manual Dug Bored Piles
Hand-dug caisson is a very simple and low cost to formlarge-size bored pile due to the following reasons:
No heavy equipment is required except powered tools
Requires very little working space
Can work for a number of piles at the same time Can work at very difficult condition such as steep slope
Boulder inside the bore can be cut fairly easily by human
worker.
The only drawback is that it is very dangerous for workerworking inside the caisson. Therefore, in 1998, the use of
hand-dug caisson was banned due to the high accident rate.
However, under special condition (e.g. work in steep slope),
approval can still be obtained subject to the fulfilment of
certain safety requirements.4/19/2013 24
-
7/28/2019 Pile Installation Methods_Bhushan
25/36
Manual Dug Bored Piles
The Manual dug piles are mainly divided
into:-
a.Piles using Caisson
b.Piles using chisel and grab
c.Reverse Circulation Method
4/19/2013 25
-
7/28/2019 Pile Installation Methods_Bhushan
26/36
Piles using Caisson
4/19/2013 26
-
7/28/2019 Pile Installation Methods_Bhushan
27/36
Piles using chisel and grab
4/19/2013 27
-
7/28/2019 Pile Installation Methods_Bhushan
28/36
Piles using Reverse Circulation Drilling
4/19/2013 28
-
7/28/2019 Pile Installation Methods_Bhushan
29/36
4/19/2013 29
-
7/28/2019 Pile Installation Methods_Bhushan
30/36
Foundation design of Bandra-Worli
Sea Link (BWSL)
The Bandra-Worli Sea Link is primarily
meant to provide an alternative to the
Mahim causeway route that is
presently the only connection
between South Mumbai and
the Western and Central suburbs.
In the first phase it will connect
Bandra to Worli whereas in the
subsequent phases the plans
are to take it further to Haji Ali
and then to Nariman Point.
4/19/2013 30
-
7/28/2019 Pile Installation Methods_Bhushan
31/36
Pile Design of BWSL
The foundations for the BWSL project consist of1. 120nos of 2.0m piles
2. 484nos of 1.5m piles
The project's site geology consists of basalts, volcanic tuffs
and breccias with some intertrappean deposits The major engineering problems that needed suitable
solutions before proceeding with the work were as follows:
Highly variable geotechnical conditions of the foundation
bed as explained above. Highly uneven foundation bed even for plan area of one pile.
Presence of Intertidal Zone (Foundation Bed exposed in
low tide and submerged in high tide).
4/19/2013 31
-
7/28/2019 Pile Installation Methods_Bhushan
32/36
Problems encountered during
Pile Driving Reverse Circulation Drilling method is adopted for foundation construction. The
highly uneven foundation beds and the presence of intertidal zone brought in lots
of difficulty in terms of Liner pitching.
This problem was solved by constructing a gabion boundary at the bed level
around the casing, pouring concrete between the casings to make an artificial
penetration of the casing. After setting of the concrete under the water, drilling was
commenced using RCD.
4/19/2013 32
-
7/28/2019 Pile Installation Methods_Bhushan
33/36
Problems encountered during
Pile Driving It is interesting to note that loss of water head during continuous
drilling operation was a major problem while working in the intertidal
zone. This water head loss lead to very slow production rate and
very high consumption of drill bits. To overcome this problem, pits
were made in the low tide at each foundation location using an
Excavator and the casing was placed at the bottom of the pits.
Then the casing was placed
in the pits and was concreted
to make an artificial penetration,
maintaining the proper
water head for continuous drilling.
4/19/2013 33
-
7/28/2019 Pile Installation Methods_Bhushan
34/36
Problems encountered during
Pile Driving For several locations, cofferdam construction using steel liner
and sheet piles, was not possible due to very hard and
uneven strata.
Here the problem was solved using circular steel caissons.
These caissons were fabricated outside and towed to locationusing A-frame barge. The caissons were sunk at the location
using counterweights.
The unevenness at the bottom was sealed using the gabion
method. The benefit of this method was that it completely
eliminated deployment of resources like Jack up Platform,Crane, Vibro hammer, Compressor, etc. for liner pitching.
It also eliminated substantial amount of field works and is
pre-fabricated in principle.
4/19/2013 34
-
7/28/2019 Pile Installation Methods_Bhushan
35/36
References
Textual Content Foundation design and construction
GEO Publication No. 1/2006, Hong Kong
Foundation analysis and design
by Joseph E. Bowles Geotechnical Engineering
by V.N.S.Murthy
Images:-
www.images.google.com
Case Study:-
Making of BWSL - www.hccindia.com
4/19/2013 35
-
7/28/2019 Pile Installation Methods_Bhushan
36/36
4/19/2013 36