Pile Work Method Statement
Pile Work Method Statement
09 May. 2019 ⧫ Author by Mr Sirey Bunhuot
6. Construction Schedule
09 May. 2019 ⧫ Author by Mr Sirey Bunhuot
TABLE OF CONTENTS
1. General
Description
2. Organization
of the work
4. Materials
5. Work
procedure
6. Construction Schedule
7. Construction Order of Pile
8. Pile test
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1.
General
Description
This pile works method statement describes the details of the
bored piles for the building construction . The details include organization of the pile
works, equipment, materials, the work procedures and the pile test. Actual
size, length, location of the piles shall be submitted in the shop drawings
separately and be approved by the Employer.
2. Organization of the work
The pile works are carried out by the organizations with relevant
roles indicated in the organization chart of the pile works below.
Organization
chart of the pile works
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3. Machine and equipment
Machine and equipment to be used for the pile works are shown
below.
Piling Machine: Sumitomo
SD205-2, 1 No.
KOBELICO SOILMEC RT-3, 1No.
Welding machine 2 Nos. for
each site
Concrete pump 1 No. on
concrete casting
Dump truck 10 ton, 1No. for
each site
Excavator ( 0.6 m3) 1No. for
each site
Bentonite plant 1set for
each site
Setting out plans are shown in the Appendix 1 and Appendix 2.
4. Materials
Concrete:
Ready mixed
concrete
Supplier: CPAC Cambodia LTD.
Supplier’s product code:
ZBDM32B3K0, SL16-21 (Fc=28 MPa in cylinder test piece)
Reinforcement
Supplier: Vina Kyoei Steel
Ltd.
Standard &
grade: JIS G3112 , SD390
*JIS G3112,
SD390 will be used for this project in place of ASTM A615 grade 60(Fy=420 MPa).
Tensile test result will be submitted with reinforced concrete work method
statement.
5. Work procedure
5.1. Preparation works
Prior to the commencement of
the cast‐in‐place concrete pilling
works, the temporary working platform for each pile shall be prepared, leveled
and if necessary, to stand the weight of bored piling machine without any
obstacles at the surface of the ground. And if it is not sufficient enough to
stand the weight of bored piling machine, steel plate will be placed to serve
as equipment working platform. Slurry setup shall be prepared near pile for
easy installation of Bentonite slurry supply to bore hole. Check level of
equipment of drilling machine and vertical of Kelly bar.
5.2. Setting Center
Point of Bored Pile
Bored Pile center location
will be set out by Survey equipment (Total station), and offset marking shall be
prepared in at least two directions at 3.00 meter away from the center of bored
pile location.
5.3. Temporary Casing
Installation
After laying out pile
center, it shall be pre‐drilled using drilling machine with Kelly bar. Bentonite
shall be supplied to prevent collapse of the drilled hole.
The length of casing shall
be considered and justified based on the soil condition and underground water level
to maintain the stability of the pile excavation against collapse. Calculation
regarding length of temporary casing is 4.5 meter. Inner diameter of casing
shall not be less than the specified size. The temporary casing verticality and
stability during the installation and non‐movement during drilling shall
be checked. The casing shall be plumbed and checked for eccentricity against
offset points. Tolerance of casing center position shall not be more than 75mm of the plan position in the horizontal plane and
the tolerance of the borehole verticality is 1/100. Installation of steel
casing fixed with the support casing’s ear on the steel plate and use the crane
for installation and extracting casing.
5.4. During Drilling
and Casting
During drilling excavation,
all hole of cast‐in‐place concrete pile should
be excavated to the design length within the required tolerance. Excavated
soil from piles will be cleared from the boring locations by means of an
excavator and a dump truck as boring proceeds. Excavated holes shall be
protected from collapse by using Bentonite slurry. Most of stratums the pile
penetrating through are low strength cohesive soil and sand, Bentonite will be used
to make up mud slurry in drilled hole to keep the pressure around the wall of
the hole and protect the hole and level Bentonite at least 1m higher than water
table from collapsing. Proposed mix 25Kg Bentonite per cubic meter of water and
before use it need to keep 24 hours of mixing. The quality of Bentonite mud
must be checked and adjusted of the requirement regularly and after the
drilling process. Testing of Bentonite slurry before during and after bored
pile drilling:
Bentonite slurry is made use
of circularity in construction process through a Bentonite circulation system that
will be arranged at site in order to avoid volume loss of Bentonite.
5.5. Installation of
Steel Cage
The length, type
and size of the steel cage shall be in accordance with the approved shop drawings and the specifications. The cages
shall be provided with stiffening rings and others accessories to enable
handling, lifting and installation without permanent deformations.
Concrete roller type spacers
wired to the cage shall provide lateral support and ensure adequate concrete
cover. Spacers shall be placed at 3 equal levels of each 12m
cage with 3 nos. at each level. Top 1 m of the main bars shall be protected by
polythene sheet wrapping to prevent direct contact of the concrete.
Steel cage shall be
installed to the borehole free from dirt, loose rust or scale, paint oil or
other nonmetallic coating that will reduce bonds. It will be then installed one
by one. The lower steel cage will be put into the casing and temporarily fixed
at the section to be spliced with the next steel cage. Sample steel gage
spicing 50% welding and 50% Binding wire (rebar wieldable). When the steel cage
reaches the designed level, it will be suspended from top of the casing by hang
rebar. The top level of the steel cage will be confirmed in comparison to that
of the casing. The level of the hanger bar to be weld on the top casing shall
be measured and marked.
5.6. Installation of
Tremie Pipe
Install the tremie pipe
Platform on top of casing borehole before install tremie pipe. Since the tremie
Pipes are segmented and connected by spiral type, these are lowered piece by
piece until it reaches to the bottom of the borehole in order to have enough
clearance in discharging of concrete. The top of tremie pipe is fitted with a
concrete hopper. Tremie pipe plug to prevent high drop of concrete and mixing
with the Bentonite at the first cast. Bottom of the tremie pipe least than 30cm
to toe of borehole.
5.7. Concreting
Common method of concrete
placement for bored pile is by direct pouring, but if direct pouring is not possible
due to high difference of working plate form top of casing elevation, pump
Crete or crane and bucket method will be used. Scaffolding and supports for
working platform shall be installed. All joints of the tremie pipes are water‐tight
in order to avoid the entry of water into the pipe that might cause the
segregation of the concrete. Level of concrete in the pipe will be checked and
continuous record shall be done by mean of measuring tape with attached weigh.
Composition and
specification of concrete in use shall be approved mixing in the trial mixing
for the pile concrete.
Pouring concrete will stop
when the good concrete level is higher than the pile cut‐of
level min. of 0.6m, and depend on the top of the soil formation, it can be
increased if the soil is very loose and silty.
5.8. Removal of
Temporary Casing
After completion of concrete
casting, tremie pipe and working platform shall be removed. Temporary casing
shall be removed vertically and gradually by crane. Elevation of top of
concrete should be measured to confirm the actual elevation of concrete after
removal of casing.
5.9. Back Fill
After temporary casing
removal, borehole shall be backfilled by excavated soil to fill up the empty
boring length. In case that backfilling is delayed 24hrs to avoid soil mixing
with the fresh concrete and some reason, empty bore shall be covered by steel
plate to prevent any accidents such as falling down inside the hole.
5.10. Work flow chart
Above
mentioned procedure in shown in the following flow chart.
6. Construction Schedule
Expected schedule for pile work is as follows which is including
mobilization, test piling ,main pilin work and demobilization.
7. Construction Order of Pile
Pile construction will be started from the back side of the site (center
line 11) and proceed forward to entrance direction (center line 1).
Work zone will be divided in 5 zones. It will take about 7 days
to complete pile work per zone. Detail of construction order of pile is as
follows.
8. Pile test
8.1 TEST PILES
Two numbers of piles for each site shall be constructed as the
test piles other than the working piles. Location, type and length of the test
piles shall be indicated in the shop drawings and approved by the Employer
prior to the commencement of the pile works.
8.2 DYNAMIC PILE TEST
The test piles shall be tested of their load capacity by the
dynamic pile test. The detail of the dynamic pile test shall be submitted in
separate method statement.
The End
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# Author by: Mr. Sirey Bunhuot
# Tell : 078 474759
# Email : bunhuotf@gmail.com
# Wedsite : brofy-es.bolgspot.com
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Engineer : Sirey Bunhuot
Location : Phnom Phenh
Project year : 2019
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