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thuyết minh biên pháp thi công cọc khoan nhồi metro HCM cienco 6 method bored pile onland REV.B English thuyết minh biện pháp thi công cống tròn×thuyết minh biện pháp thi công mặt đường láng nhựa×ong vach bien phap thi cong coc khoan nhoi va thi cong co su dung vua set×biện pháp thi công cọc khoan nhồi dưới nước×mẫu biện pháp thi công cọc khoan nhồi×trình bày biện pháp thi công cọc khoan nhồi×
HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land Ho Chi Minh City Urban Railway Construction Project PROJECT TITLE: Ben Thanh - Suoi Tien Section (Line 1) Construction Package 2 : Civil (Elevated & Depot) Method Statement of Bored Pile Construction on Land REVISION STATUS REV. No. DATE B 19th Feb. 2013 DESCRIPTION SECOND ISSUE PREPARED BY NAME SIGNATURE DATE REMARKS CHECKED BY APPROVED BY HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land TABLE OF CONTENTS 1 INTRODUCTION.......................................................................................................3 0.1 OVERALL OF PROJECT .......................................................................................3 0.2 GENERAL ..............................................................................................................3 0.3 WORK SCOPE........................................................................................................3 1 CONSTRUCTION PROCEDURE...................................................................................4 1.1 WORK FLOW-CHART.............................................................................................4 1.2 WORK PROCEDURE..............................................................................................6 (1) Preparation Works................................................................................................6 (2) Setting center point of the bored piles.................................................................7 (3) Assembling Guide frame......................................................................................8 (4) Setting of the temporary casing...........................................................................8 (5) Drilling work..........................................................................................................9 (6) 1st Cleaning bottom of the holes & Changinh Bentonite...................................12 (7) Fabrication and Installation of the rebar cage....................................................13 (8) Setting of Tremie Pipe and Re-cleaning (2nd Time Clearing) of Bored hole.....15 (9) Casting concrete................................................................................................16 (10) Removal of Temporary Casing.........................................................................18 2 RESOURCES TO BE USED........................................................................................18 3.1 EQUIPMENT TO BE USED...............................................................................18 * The equipment (type and quantity) might be changed depending on the site situation. ......................................................................................................................19 3.2 ORGANIZATION....................................................................................................20 2.1 RESPONSIBILITY OF STAFF...............................................................................20 3 CONTINGENCY AND SOLUTION...............................................................................21 3.1 CONTINGENCY OF DRILLING WORK................................................................21 3.2 CONTINGENCY OF SUCCESSIVE WORK..........................................................22 4 GROUND MOVEMENT AND SOLUTION....................................................................22 4.1 GROUND MOVEMENT.........................................................................................22 4.2 SOLUTION.............................................................................................................23 5 QUALITY CONTROL....................................................................................................23 5.1 QUALITY CONTROL.............................................................................................23 5.2 SEQUENCE OF Inspection and Test ....................................................................23 5.3 Tolerance / Ranges................................................................................................26 5.4 Inspection and Test Personnel...............................................................................26 5.5 Laboratory..............................................................................................................27 5.6 Quality Control Plan for Bored Piling Works..........................................................27 6 HEALTH, SAFETY AND ENVIRONMENT...................................................................28 6.1 HSE Training..........................................................................................................28 6.2 PPE........................................................................................................................29 6.3 Tool Box Meeting (TBM).........................................................................................29 6.4 HSE Inspection......................................................................................................29 6.5 Safety Control Measures.......................................................................................29 (1) Crane and Heavy Equipment Control...............................................................29 (2) Electrical Works..................................................................................................29 (3) Fire Fighting Equipment and Fire Prevention....................................................30 6.6 Environmental Control Measures...........................................................................30 (1) Water Pollution Control .................................................................................30 (2) Protection of Air Quality.....................................................................................30 (3) Noise Control......................................................................................................30 (4) Others.................................................................................................................31 HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land 7 MERGENCY RESPONSE CHART.............................................................................32 ACCIDENT / INCIDENT.................................................................................................32 1 0.1 INTRODUCTION OVERALL OF PROJECT - 0.2 Project name: Ho Chi Minh City Urban Railway Construction Project Line 1, Ben Thanh - Suoi Tien Section. The project comprises about 17,24 km of elevated rail way from Km2+360 to Km19+591.37 (including 5 special bridges) and 1 depot. Location: Starting at District 1 and ending at Long Binh Ward, District 9, Ho Chi Minh City. GENERAL The objective of this method statement is to describe the construction methodology and procedure for bored pile work on land of HCMC Metro Project. The bored pile construction technique is to construct independent circular cast in-situ reinforced concrete piles from the designed depth to the designed cut-off level. Required site management controls for cast-in-place concrete piling works by using Earth Drilling Machine, the type of bored piling rig shall be so selected as to suit the required drilling length and/or underground condition. The sizes of the piles to be covered by this method statement are diameter 1500mm, 1200mm & 1000 mm. 0.3 WORK SCOPE This method statement includes below scope of works. - Drilling works: D=1,500mm, 1200mm & 1000 mm. - Installation of Rebar Cage. - Casting Concrete. Temporary steel casing, of which diameter is 50~100mm larger than designed bored pile diameter, will be installed. The boring works will be carried out until the designated toe level. Bored hole is filled with Bentonite slurry once the boring works commenced. Upon completion of the boring works, the reinforcement rebar cage will be lowered into the borehole. Cleaning borehole shall be performed before the installation of reinforcement rebar cage, and then the casting concrete of the bored piles will be taken place. Bored piles with different diameters and lengths will be constructed in accordance with the construction working drawings. HCMC Metro Cp-2 Project TITLE : 1 Method Statement of Bored Pile Construction On Land CONSTRUCTION PROCEDURE 1.1 WORK FLOW-CHART The work sequence of the bored pile construction is depicted by the following flow-chart. Preparation Works Setting center point of bored pile Assembling Guide frame Setting of the Temporary Casing If necessary Drilling Works KODEN Test 1st Cleaning of the Bottom Hole Installation of the Rebar Cage (including Sonic and core tubes) 2nd Cleaning of Bottom Hole (if necessary) Casting Concrete Removal of the Temporary Casing Backfill with suitable material Inspection: - Center point Deviation - Vertical of casing - Level of casing top Inspection: - Depth of bored hole - Property of Bentonite Inspection: Diameter of bored hole Vertical of bored Inspection: - Rebar cages (at yard) - Sonic and core tubes - Depth of bored hole by using rebar cages Inspection: - Property of Bentonite - Depth of bored hole Inspection: Slump of concrete Level of concrete rising Center of Pile - Level of top concrete - Depth of bored pile by SONIC Test Core test (if necessary) Grouting SONIC and core tubes Completion The following diagram shows the continuous sequence of bored piling works HCMC Metro Cp-2 Project TITLE : Stage 1 Method Statement of Bored Pile Construction On Land Stage 2 Stage 3 1.Pre-boring for temporary casing 1. Temporary casing installation installation by vibro hammer. 1.Pumping of bentonite slurry for maintaining bored hole 2.Drilling of bored hole from EGL to Design Toe Level Stage 4 Stage 5 1.Desanding the complete bored hole 2.Bentonite in bored hole will be pumped back to bentonite plant for treatment. 1.Lowering of reinforcement to the bored hole. 2. Hanging the rebar cage at the designed level. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land Stage 7 Stage 6 1.Concreting of bored pile. 2.Pumping of displaced bentonite back to bentonite plant. 3.Overcasted concrete 500mm above design COL. 1. Extracting temporary casing after the completion of concreting 15 to 20 minutes. 2. Backfilling the bored hole with suitable backfilling material 1 to 2 hours after the completion of concreting Fig.1 Sequence of Bored Piling Works 1.2 WORK PROCEDURE The detail work procedure is described as follows. (1) Preparation Works Prior to the commencement of the Cast-in-place concrete piling works, the site will be cleared and leveled to stand the weight of Bored Piling Machine without any obstacles at the surface of the ground and also prepared to form working platform with sufficient working space. 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. Temporary drainage system shall be provided around the platform so that the platform and the surrounding area are kept dry and accessible all the time. The temporary access road shall be made in case that existing road is not available for supplying material and mobilizing to equipment. Bentonite mixing tank will be installed for fluent execution of the work maintaining including connection of pipe or hose to supply bentonite for the bored pile location. It will be checked from time to time for any possible spillage of bentonite slurry as per environmental requirement. The density and consistency of the concrete for the bored piles shall conform to the tremie HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land casting method and the maintenance of sufficient workability (slump) of all the concrete during the casting and handling period, including calculated allowance delay time, shall be secured by a design mix (including the necessary retarders and plasticizers) which is tested by trial mixes prior to the pile construction. The number of tank used for bentonite mixing plant shall be calculated to make sure that the volume of mixed bentonite slurry is enough for carrying out drilling work continuously. Typical layout of equipment and facilities set up for bentonite solution is shown below. Precipitation Tank 3 Precipitation Tank 2 Precipitation Tank 1 Circulation Tank Withdrawal Tank Mixing Tank Waste Tank Mud Screen Circulation Pump Cyclone Supply Pump Supply Pump Sand Pump Another Hole Drilling Hole Base Machine Drilling Hole * Note: Flow of stabilization liquid Concreting * This layout could be changed according to site condition Fig.2 Layout of equipment and facilities set up (2) Setting center point of the bored piles Positioning drilling hole is based on the approved drawings, positioning benchmarks and piling arrangement layout for specifying positions of pile center in compliance with the HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land approved design. Specifying the position of the pile center is performed by electronic total station. The position shall be approved by the Employer’s Representative. In addition, subsidiary benchmarks shall be set up by steel piles for direction of pile center and the pile center shall be checked again upon sinking temporary well casing. These positions shall be protected and maintained until sinking and completing inspection of the well casing. Checking of the bored hole location shall also be carried out for all the piles after the commencement of boring, but not later than when boring has reached the top of the first stiff layer. Pile center Subsidiary benchmark Datum point Fig.3 Setting out center of Bored pile (3) Assembling Guide frame Assembling guide frame will be prepared before Setting of the temporary casing. (4) Setting of the temporary casing Bored pile construction will be commenced from setting out pile location and pre-drilling and installing temporary casing. The length of the casing will be considered and justified based on the soil condition and underground water level for maintaining the stability of the pile excavation holes against collapse, the casing length is from 6m to 9m. The top of temporary casing will be extended about 0.5 meter above the ground level. In installation of temporary casing, the verticality and stability will be checked and nonmovement during drilling shall be kept. Inner diameter of casing pipe will be at least 5 ~ 10cm larger than bored hole diameter. The casing will be plumbed and checked for eccentricity against reference pegs, or it will be checked with survey equipment at the top of the casing with the same elevation aside from the location frame installed above ground level. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land Fig.4 Installation of temporary casing (5) Drilling work The design length of piles will be specified in approved drawings. During drilling excavation, all holes for cast-in-place concrete pile should be excavated to the design length. Excavated holes will be protected from collapse by the provision of bentonite slurry and temporary steel pipe casing. Fig.5 Casing HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land Fig.6 Casing a) Bentonite slurry All properties of chosen bentonite shall be tested and the test results shall be submitted to the Employer’s Representative to get approval before using. During drilling process of bored hole, the soil wall will be protected from collapse by the provision of bentonite slurry and temporary steel pipe casing. Prior to drilling works, the stabilization liquid as the bentonite suspension will be prepared and tested to meet the criteria which will be proposed before commencement. Bentonite will be mixed thoroughly with clean fresh water to make a suspension which will maintain the stability of the drilled hole for the period of casting concrete and complete construction. Dry powder Bentonite is mixed with clean water according to required ratio by mixing machine and stored in the tanks which will supply to bored hole. The drilling fluid properties of bentonite slurry will be measured by taking samples before concreting. The density of freshly mixed bentonite slurry will be measured as a check on the quality of the suspension being formed. b) Setting up of Bentonite Plant The following are the various stages of works in the setting up of site facilities: Setting up Installation of desander unit. Preparation and levelling of ground. Installation of bentonite silos. Setting up of bentonite plant facilities. Layout of bentonite and water piping systems. Pre-mixing of bentonite slurry on site. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land c) Bentonite Slurry Mix Design Basic function of bentonite is to act as a stabilizing agent for the bored hole. In soil with high clay content, the bentonite slurry becomes very thick during excavation due to the suspended clay particles. The thick slurry becomes difficult to pump for desanding. To avoid this problem, a polymer / sodium bi-carbonate is added to the slurry. d) Testing Bentonite Slurry Bentonite Slurry Testing: The following tests will be conducted on bentonite slurry at the beginning and during bored pile construction period. 1. Viscosity test - test on site 2. Sand Content – test on site 3. Density test - test on site 4. pH meter test - test on site Bentonite characteristics have to meet the requirement (refer to Sub-clause 6.3 Tolerance/Range, page 24-25). The bentonite properties shall be measured by taking samples at the bottom of bored hole before concreting. All checking of bentonite slurry shall be carried out complying with the criteria proposal. The measuring device shall be calibrated to read in the minimum unit of 0.01gm/ml. 0.5-1.0 m above G.L Bentonite Fig.7 Bentonite Slurry HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land e) Drilling works Temporary casings shall be free from any significant distortion. They shall be of uniform cross- section throughout each continuous length. During concreting, they shall be free from internal projections and encrusted concrete which might disturb the proper formation of piles. From the ground level to one meter above the toe of the temporary casing will be drilling without stabilization bentonite. The measurement of the depth of drilling bucket shall be closely monitored when it gets near of the toe of the temporary casing. After putting bentonite into the borehole, drilling work will be continued and the top level of bentonite slurry will be maintained 1.5m higher than ground water level or equal with ground level for prevention of cave-ins or bored hole collapses. Based on the soil properties, drilling speed is adjustable in order to maintain the drilling accuracy. The soil materials encountered in the bored pile drilling shall be checked to confirm whether the actual soil conditions are similar to those assumed based on the geotechnical investigation boreholes or not. During the drilling work, the verticality of bored hole will be checked by plumb with string line or theodolites from two directions in 90 degree. And the depth of bored hole will be checked for the conformation of borehole condition. When the bucket is lifted up, the bucket is to be rotated reversibly to release from the bottom and to be lifted up slowly to protect the hole from collapse. Kelly-Bar shall be kept at the centre of the casing because drilled holes start to bend with Kelly-Bar’s deviation from the centre. In case any the deviation is found, the drilling should be operated slower than usual and to correct the Bar’s verticality. After a borehole is formed to the designated depth, sonic caliper test (Koden Test) shall be carried out for checking the depth, diameter and verticality of the boreholes. Bentonite introduced into the borehole achieves the stabilizing effect by ensuring that the pressure inside the borehole is greater than the horizontal soil pressure and groundwater pressure, at all depths. Piles shall not be bored so close to the piles, which have been casted not long ago with workable or unset concrete. The piling may disturb the fresh concrete in the neighboring piles. Boring and excavation for a pile shall only be commenced 24 hours after completion of any pile within a radius of 6.0m, center to center, and only after the concrete strength of the neighboring pile reaches 15N/mm2. The excavated material and disposal bentonite will be kept in tanks or containers then transported to approved disposal areas by special trucks. The proposed disposal areas will be submitted to the Employer’s Representative for approval later and separately. (6) 1st Cleaning bottom of the holes & Changinh Bentonite For the supply of fresh bentonite slurry, tank for fresh bentonite slurry will be installed at the position which is separated apart from the bentonite pit. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land The sequence of cleaning work for the bottom of hole is as below: - Using cleaning bucket to remove lumps of clay, coarse sand and gravels at the bottom of the borehole. Then, - Using reverse circulation method or air lifting method for replacing sedimentation of slime with good slurry. After cleaning work, the depth of hole will be measured by measuring tape connected to a plump bob. Measuring of hole will be carried out at the center and four corners of the hole. Fig.8 Cleaning by cleaning bucket (7) Fabrication and Installation of the rebar cage Fabrication of rebar cage: Steel bar shall be tested when delivery to site and only approved steel bar will be used. Rebar cages, sonic tube and core tube will be fabricated and assembled according to the approved construction working drawing. After the completion of fabrication for one segment of rebar cage, this segment shall be carefully kept in the dry and stable condition at stockyard which is elevated about 20 cm higher than ground surface level. Condition of re-bar cage will be checked and cleaned constantly. If some soil or rust are pound remained on the re-bar cage, all of them shall be removed before the installation of re-bar cage. Additional reinforcing ring will be used for hanging of rebar cage segment and for the cage stabilized against distortion. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land Fig.9 Reinforcement fabrication Installation of rebar cage and sonic tubes and core tube: After the 1st cleaning of borehole is completed, the rebar cage will be installed carefully in order to avoid the wall of the borehole from collapsing. The lowest rebar cage segment will be put into the casing and temporarily fixed at the section to be spliced with the next rebar cage segment. When the rebar cage reaches the designed level, it will be suspended from top of the casing. The top level of the rebar cage will be confirmed in comparison to that of the casing. The ultra-sonic tubes and core tube will be fixed to rebar by additional bar and ties to the rebar cage. Top level of the sonic tubes and core tube will be positioned approximately 15cm above the ground level and checked for the rigidity and watertight of tubes during installation. The sonic tubs and core tube will be poured with water and covered on the top of tubes prior to casting concrete. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land Fig.10 Installation of the rebar cage (8) Setting of Tremie Pipe and Re-cleaning (2nd Time Clearing) of Bored hole a) Setting of Tremie Pipe Tremie pipes of dia. 8-10 inches shall be used. The tremie pipes with standard length, such as 0.5M, 1M, 2M, 3M and 6 M, shall be used. Since the tremie pipes are segmented and connected by bolts as a flange type and a rubber gasket will be used therein to watertight, these are lowered piece by piece until it reaches to the bottom of the borehole. And the tip of tremie pipe will be at least 300mm away from the bottom of bored hole in order to have enough clearance in discharging of concrete. The top of tremie pipe is fitted with a head hopper. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land The length of each tremie pipe and the sequence of installation shall be recorded completely. Fig.11 Tremie Pipe b) Re-cleaning of the Borehole (2nd Time Cleaning) Prior to placing concrete, the depth of bored hole will be measured carefully and the bentonite slurry will be tested once again, and the second time cleaning of pile base will be carried out if required by the Employer’s Representative with 1 of 2 methods: 1. Airlifting method: Air-lift system will be used as second measure to take all slime out of the bottom of bored hole, before casting concrete. The pressure of compressed air has to be properly checked. Since stabilizing fluid is supplied to the piling hole, the compressed air will create an upward jet flow which carries the bottom sludge out of the hole. The circulating time of airlift varies depending on the amount of bottom sludge. 2. Reverse circulation method: using the capable submerged pump connected to tremie pipe for removing the slime sedimentation at the bottom of bored hole and replacing by fresh slurry. A measurement tape is to be used for the re-confirmation of drilling depth and effect of cleaning work. The concrete placing will be started as soon as possible (approx. in 30 minutes) after second cleaning of bottom of bored hole. And before casting concrete, it will be confirmed by measurement tape that the sedimentation has been removed completely. (9) Casting concrete Fresh concrete shall be applied to cast-insitu pile and concrete will be mixed at batching plants then supplied to site by mixer trucks. The proportion of ready mixed concrete shall be tested and approved by the Employer’s Representative before using. Only specified ready mixed concrete will be used. The summary is as below: HCMC Metro Cp-2 Project TITLE : Strength class/ Description Grade 30 Max. size of aggregate (mm) 20 Method Statement of Bored Pile Construction On Land Slump (cm) 18 to 25 Compressive strength at 28 days (Cylinder) 30 N/mm2 Cement Contents 356Kg/m3 Prior to commencement of the concrete casting work, the following checking will be executed for preventing the tremie pipe from blocking. * Workability of concrete. * Selection of the suitable tremie pipe (diameter, length per pipe and joint) * Check of pipe joints leakage (visual Inspection) Once again taking of Bentonite samples at the bottom of the bored hole by special equipment and testing shall be performed before pouring concrete. Concrete will be placed and poured directly to the bored hole in one continuous operation from tip to cut-off elevation by tremie pipes and this operation will be carried out in such a manner that segregation of concrete is avoided. The tip of the tremie will generally be approximately 2.0m lower than the casting concrete surface. A sliding plug or similar barrier will be placed within the tremie pipe to prevent direct contact between the first charge of concrete and the water or bentonite. Fig.12 Casting concrete The schedule for casting concrete will be confirmed in order to ensure concrete pouring continuously without interruption. Hence the top of concrete is contaminated by mixing with stabilization liquid; extra volume of concrete is to be used for confirmation of the clean HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land concrete. The height of extra or surplus concrete is proposed to be more than 0.5m from cut-off level; however this may be adjusted in consideration of the site condition. Tremie pipes are chocked with tremie support and clean immediately after disconnection to avoid clogging of concrete inside of the pipes. It is required to check the elevation of casting concrete in the bored hole by special tape and plumb to control elevation of the tremie pipe bottom suitably and to detect immediately any collapsing or narrowing of bored holes. Collapse or necking of borehole may be detected by comparison of the calculated volume of the bored hole with the actual volume of concrete poured into the borehole. (10) Removal of Temporary Casing Temporary casing shall be withdrawn 15 minutes to 20 minutes after concreting by using the draw and spin system of drilling machine or using vibro-system in vertical direction to make sure the stability of pile head and degree of accuracy of pile center. After removal of temporary casing, from 1 hour to 2 hours, the bored hole will be filled by soil and/or sand. 2 RESOURCES TO BE USED 3.1 EQUIPMENT TO BE USED For the successful implementation of bored piling works, the following equipment will be mobilized. The list of equipment for a typical working party is shown below. Bored pile works will be carried out with the following equipment. The List of Equipment for One Typical Working Party No. Item 1 Drilling machine Kelley or RCD equivalent machine 2 Service Crane 40~50t class crawler type 4 Diesel Generator For welding 6 Airlift pipe For cleaning borehole 7 Water Pump For the circulation of bentonite slurry 8 9 10 Description Pouring concrete platform Bar Cutter machine Bar Bending Machine 11 Air Compressor 12 Tremie Pipe Remarks or For excavation of bored hole For handling of steel cages and concreting works For casting bored pile For fabricating rebar cages For fabricating rebar cages For airlifting (Cleaning) 80m For cleaning borehole HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land 13 Drilling Bucket D = 1000~1500mm Boring tools 14 Cleaning Bucket D = 1000~1500mm Boring tools 15 Casing Pipe D = 1050~1550mm For excavating of borehole 16 Bentonite Tank 17 18 19 20 Concrete Mixer Truck Bentonite Desander Survey Equipment Measuring Tape with Plumb Bob 21 Empty tanks 22 Excavator For the circulation of bentonite slurry 6 m3 For bored pile casting Total Station / Auto Level Setting center point and elevation pile For measuring depth of borehole For containing excavated material and disposal bentonite For preparation work and support work * The equipment (type and quantity) might be changed depending on the site situation. HCMC Metro Cp-2 Project TITLE : 3.2 Method Statement of Bored Pile Construction On Land ORGANIZATION Organization chart for Cast-in-place Concrete Piling Work are shown below. Construction Manager (Mr. Kim Dong Wan) Quality Manager (Mr. Myung Jai Sin) Safety Manager (Mr. Hwang Ki Ha) Environmental Manager (Mr. Tran Thanh Lap) Survey Team Site Manager (Mr. Lee Jung Sun) Site Engineer (Mr. Mai Song Thao) Subcontractor’s Project Manager Subcontractor’s Engineer Operator 2.1 Skill Labor Common Worker Electrician Welder RESPONSIBILITY OF STAFF The following staff / personnel will be deployed on site to comply with the approved construction drawings and as per the specifications and the construction programmed. Project Manager – Overall Supervision Construction Manager – Coordinate with the Employer’s representative for the Execution, Quality and safety Site Engineers, Surveyor & QA/QC Staff – Execution, Quality and Safety, Follow Up Quality Control Procedures and submission of quality Forms and records on daily activities QA/QC Manager: In charge of laboratory’s works; compose QC Plan; inspect materials and construction works’ quality; ensure the quality control implementation in according to ITP Responsible for inspection and establishes all relevant procedures and initiates coordination with relevant inspection parties. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land HSE Manager: Carry out the necessary measures and/or procedures to ensure the implementation of HSET Plan (Health, Safety, Environment, and Traffic). 3 CONTINGENCY AND SOLUTION The possible contingency and solution during piling work will be described below. 3.1 CONTINGENCY OF DRILLING WORK (1) Sand piping The steel standing casing will be installed into the ground to protect the drilled hole from collapsing due to the weight of working machines. However, piping may occur due to insufficient penetration depth or penetrating into a sand layer. This occurrence may result in water level dropping suddenly, drilling surface collapsing, and the standing casing lowering or tilting. To solve this situation, either increases the casing length or withdraws the casing and backfill immediately and re-excavate after the backfill consolidated. (2) Collapse because of excessive loads Potential collapse may occur due to the excessive loads. Before drilling, equipment which is not necessary should be removed for drilling. Increasing the viscosity of slurry or the length of standing casing may reduce the risk of collapse. When large collapse happens, all the equipment will be removed and the hole will be backfilled immediately. For several days, the pile could be drilling again after covering the ground of the borehole with steel plates and increasing the casing length (if necessary). (3) Insufficient water head Insufficient water head in the drilled hole may result in the collapsing of the drilling surface. Spillage leakage into ground may occur while the high permeable layer is encountered. Therefore, the water level within the drilled hole shall be inspected regularly and frequently. Additional slurry or other solutions may be needed to keep slurry from flowing into the high permeable layer. (4) Vibration effect The distribution of heavy equipment should be located evenly around the piling area to avoid excessive loads or unbalanced loads. Also, vibration effect may occur due to earth tremor or ground shaking caused by heavy equipment. According to previous working experience, heavy equipment should be placed at a good distance away from the borehole location to ensure the safety of equipment and personnel during piling work. (5) Hindrances in pile position In some occasions, huge rock or rotten wood may be encountered during drilling. Care and patience should be taken to break or penetrate such objects. Increasing working torque or rate may cause ground shaking and damage the drilling surface. (6) Drill bit and pipe dropping HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land During the drilling process, it is possible that the drilling bit and pipe snaps and drops suddenly down to the drilled hole. When this accident happens, workers stop drilling and try to hook and drag the dropped bit and pipe immediately with the wire with hook of crane. 3.2 CONTINGENCY OF SUCCESSIVE WORK (1) Rebar cage dropping into the drilled hole When the rebar cage drops into the drilled hole, the installation should be stopped immediately. The dropped cage should be recovered by using the wire with hook, which is enough to recover the falling cage. After recovering, the condition of the cage should be check to make sure that the cage quality is still accepted for structural use. Another section will be needed if the cage is not accepted. In order to prevent the cage from falling or dropping, the connecting points among rebars and hanging bars should be carefully inspected. After removing the rebar cages the depth of borehole shall be checked again to make sure the drilled depth before re-installing rebar cages. (2) Tremie pipe dropping into the hole before concrete placing Care should be taken while inserting tremie pipes into the hole. When the tremie pipe is dropped into the hole before concrete placing, the work should be stopped. A large hook will be used for recovering the dropping pipe from the hole and resume the work. (3) Tremie pipe out of the placed concrete If the bottom of tremie pipe be out of the placed concrete due to the pipe blocked, it is a practicable choice to re-penetrate the cleaned tremie pipes into the placed concrete before the initial set of concrete, to vacuum water and slurry in the tremie pipe and to continue placing concrete. The procedure of work shall be checked carefully at the points of: The taken time should less than the setting time of used concrete and as soon as possible. The volume of bentonite slurry inside the tremie pipe. The toe of tremie pipe inside poured concrete at least 2m. The procedure of the treatment shall be recorded completely and accurately. The integrity test of the pile shall be executed after 7 days to confirm the structural capability. (4) Collapse during concrete placing When placing concrete, there are chances that the wall of hole has collapsed if the water level suddenly increases or decreases. The placing work should be stopped immediately, and check the elevation of the concrete surface carefully. Base on actual elevation and collapsed quantity, decide to stop pouring or continue placing concrete after discussion with the Employer’s Representative on site. 4 4.1 GROUND MOVEMENT AND SOLUTION GROUND MOVEMENT - The ground movement could happen due to bored piling works especially: - If borehole wall is collapsed and surrounding soils are flowing into the boreholes HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land together with groundwater. 4.2 - If groundwater flows into the boreholes together with soils at the base of the boreholes (boiling of sandy soil ground at the base of the borehole) - If groundwater level of surrounding ground was lowered SOLUTION In order to prevent ground movement during piling work, these solutions will be applied: - In case of problem arise, bentonite shall be densified and extend the temporary casing. - Bentonite shall be kept more than 1.5m above from existing groundwater level, described in fig. 13. Fig. 13 Bentonite and ground water level 5 5.1 QUALITY CONTROL QUALITY CONTROL All material will comply with the requirements in the Outline Construction Specification and the required inspection and test on site will be carried out in compliance with the ITP and quality control plan. ITP will be submitted to the Employer’s Representative separately. 5.2 SEQUENCE OF INSPECTION AND TEST HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land a) Steel reinforcement Each sample of steel reinforcement shall be tested to determine the yield stress, elongation, tensile strength, bending properties and unit mass. Each sample of reinforcement couplers for tension joist shall be tested to determine the tensile strength and the permanent elongation, if any. The method of testing shall be in accordance with JIS G 3112 or JIS G 3117 or equivalent ASTM standards. These tests shall be carried out by the consented testing authority. Rate of sampling of reinforcement are performed by the this table The number of Steel reinforcement specimens in each sample shall be as follows Reinforcement U-Clip for tension joint: 3 Each specimen of steel reinforcement shall be 1m long. Each specimen of reinforcement U-Clips shall consist of one reinforcement U-Clip jointed two lengths of bar each 500mm long. The bars shall be of the same type, size and grade as the bars to which the reinforcement U-Clips will be fixed in the Permanent Works. Each specimen of steel reinforcement shall be taken from different bars. The ends of the specimen shall be cut square before delivery to the laboratory. b) Ready Mixed Concrete HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land The ready-mixed concrete shall be obtained only from a supplier agreed by the Employer’s Representative . Contractor shall submit the Mix Design Ready Mixed Concrete to the Employer’s Representative for his approval. Ready-mixed concrete shall comply with the requirements of JIS A 5308 or equivalent Vietnamese Standards and those specified herein and shall comply with all requirements of the Contract. The concrete shall be carried in purpose-made agitators, or truck mixers, operate continuously. The concrete, shall be compacted and in its final position within 2 hours of the introduction of cement to the aggregates, unless a longer time is agreed by the Employer’s Representative. The time of such introduction shall be recorded on the Delivery Note, together with the weight of the constituents of each mix. The Contractor shall make the supplier aware of all Specifications requirements and of his program, construction methods, rates of concreting, access, and all other criteria which may affect the supplier's performance in any way. Sampling and Testing shall be in accordance with the following specification and Inspection and Test Plan No 1 Test Item Compressive strength of Cylindrical Concrete Specimens Standards JIS A 1108 or AASHTO Test Method T22 2 3 Making and Curing Concrete Compressive and Flexural Strength Test Specimens in the Field Obtaining and Testing Drilled Cores 4 Sieve Analysis of Fine and Coarse Aggregate 5 Specify Gravity Aggregate JIS A 1132 or AASHTO Test Method T23 JIS A 1107 or AASHTO Test Method T24 JIS A 1102 or AASHTO Test Method T27 JIS A 1109 or AASHTO Test Method T84 6 Related testing for Fine Aggregate 7 Specify Gravity and Absorption of Coarse Aggregate and Absorption of Fine Refer to sub-clause 5.1.2 (3) JIS A 1110 or AASHTO Test Method T85 The frequence of testing and sampling of fresh concrete at construction site are performed by the this table No 1 2 3 Item Temperature of concrete Slump of concrete Cylinder sample Frequence Remark Every truck Every truck 1 set / every 30m3, Base on Outline not less than 1 set / Construction Specifications 1pile c) Testing of Bentonite Slurry The following tests will be undertaken on the bentonite slurry to monitor the performance HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land during construction process at the minimum intervals described below: Prior to commencing excavation Prior to concreting of the pile (after desanding) The Bentonite Slurry shall be tested in the following characteristics: Property to be measured Density Sand content Viscosity Range of result at 20˚C Less than 1.10 g/ml Less than 3% 30-50s or less than 20 cP Shear strength (10 minute gel strength) for bentonite only pH 5.3 Mud density balance Sand content determination Marsh cone method *Fann Viscometer Shearometer *Fann Viscometer pH indicator strips or electrical pH meter TOLERANCE / RANGES No. 1 2 3 4 Items Density of bentonite slurry Acceptance Tolerance Sand Content of bentonite Less than 3% slurry 30~50s or less Viscosity of bentonite slurry 20cP Shear strength of bentonite 1.4~10N/m2 slurry 4~40N/m2 pH of bentonite slurry 9.5~12 6 Pile verticality 1:100 7 Steel cage installation (vertical / center) 1:200 / 15 mm 8 Concrete cover to rebar ≥100 mm 9 Slump for pile boring ≥ 180mm 10 Pile eccentricity at C.O.L ≤100mm 12 Remarks Less than 1.10 g/ml 5 11 5.4 1.4-10 N/m2 or 4-40N/m2 9.5-12 Test method than or Tremie pipe depth under ≥2.0 m concrete Removing height at top ≥500 mm concrete INSPECTION AND TEST PERSONNEL During bored pile construction, inspection and test are performed by the QA/QC engineer and laboratory’s technician. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land QC Engineers / Inspectors are selected for the project by the QA/QC Manager on the basis of qualifications and experience, from THE CONSORTIUM QA/QC Team 5.5 LABORATORY The approved laboratories will be carried out all tests, recording and reporting the results in accordance with the project’s specification as calendar specified in the Quality Control Program; Being put under the management of the QA/QC Manager; The Manager and the testing personnel shall have full capability of specialty. The laboratory shall have sufficient persons to meet the requirements of the construction schedule. Being equipped with sufficient apparatus, facilities to execute the testing work and ensure the testing standards as contracted. 5.6 QUALITY CONTROL PLAN FOR BORED PILING WORKS Each inspection activities are performed by the this table 1.0 BOREHOLE PREPARATION 1.1 The pile location will be marked by steel / wooden pin (stakes) driven into the ground, using coordinate system. Checking of Pile location Two (2) reference pins will be driven into the ground to subtend an angle of approximately 90° with the setting out pin as the origin. Check installation of temporary casing – concentric to the pile center. Checking location, verticality, displacement and Casing Top Levels. Boring will then continue using drilling fluid (Bentonite), record of strata will be made during excavation of the pile and recorded on the pile record sheet. Check sampling and testing for bentonite within the characteristics and properties required in the specifications Check the depth of bore using an end weighted measuring tape. Upon reaching the required depth, the pile base will be cleaned; the slurry will be checked as per Specifications. REINFORCEMENTS Reinforcement steel, sonic pipes, etc. will be delivered at site and checked for its origin and acceptability according to the approved certificated 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 RESPONSIBILITY Surveyor Surveyor Foreman Engineer Foreman Engineer Surveyor, Engineer Foreman Engineer / Site / Site Site / Site Foreman, QC staff Foreman Engineer Foreman Engineer / Site / Site RESPONSIBILITY Site Engineer / QC Staff HCMC Metro Cp-2 Project TITLE : 2.2 2.3 2.4 2.5 3.0 3.1 3.2 3.3 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 6 Method Statement of Bored Pile Construction On Land submission and to all relevant clauses of technical specifications. The reinforcement cages will be fabricated according to the pile design. The reinforcement cage will be identified by reference to the drawing and tag/marking shall attach to the reinforcement cage. The reinforcement cage installed with sonic pipes will be checked for cleanliness and compliance with the drawings & specifications. The cage will be lifted with caution and placed with minimum distortion. CONCRETE Concrete will be received on site and the delivery ticket be checked for correctness in accordance with the approved mix design. (Grade 30) The concrete will be tested for workability by the slump cone in accordance with specifications; Slump = Min. 180 mm If workability of concrete is within acceptable limits then collection of test samples / (cylinders) will be done as per Inspection & Test Plan (ITP). PILE CONCRETING All concrete will be placed by the tremie tube method by pouring of concrete pump or direct pouring from the transit mixer, The tremie size should not be less than 250 mm. The tremie pipe is made up of sections with sufficient length to reach the toe of the pile, sections are provided with seals. The tremie pipe will be inserted in the center of the pile to reach 300 mm above the pile toe level. The connections of Bentonite pipelines and pumps and all arrangements for concreting. Pouring of concrete into the pile borehole, the length of the tremie pipe will be shortened if necessary, but the tremie pipe should be maintained continuously into the concrete of at least 1.5 ~ 2.0 m. Concreting will continue until reaching above the cutoff level of pile. (Extra volume of concrete shall be poured above the cut-off level.) The final concrete level and the volume poured will be recorded and noted on the pile record sheet. Foreman Engineer Foreman Engineer / Site / Site Foreman Engineer / Site Foreman / Site Engineer RESPONSIBILITY Site Engineer / QC Staff Site Engineer / QC Staff Site Engineer / QC Staff RESPONSIBILITY Foreman / Site Engineer Foreman Engineer / Site Foreman Engineer Foreman Engineer Foreman Engineer / Site / Site / Site Foreman Engineer / Site Foreman Engineer / Site HEALTH, SAFETY AND ENVIRONMENT Basically, HSE control shall be done following the submitted Site Safety Plan and Site Environmental Plan. 6.1 HSE TRAINING HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land All workers who are to be engaged in Bored pile works shall be inducted and instructed by a competent person from the Contractor on safe methods of work, such as basic first aid training, safe use of cranes, slinging techniques, emergency procedures etc. 6.2 PPE All personnel shall wear mandatory personal protective equipment (PPE) at all the time such as safety shoes, hard hat, safety goggles and gloves etc. Additional PPE may require for the workers as necessary. 6.3 TOOL BOX MEETING (TBM) Every morning all Contractor staff and Subcontractors hold tool Box Meetings in their appropriate groups at site before commencing any activity including the piling works. TBM is a short meeting and one of the most effective ways to help eliminate or control accidents / incidents and enhance the safety awareness of the workers according to their work categories. 6.4 HSE INSPECTION Site Engineers / supervisors / foremen in-charge of specific work areas shall conduct daily safety patrols to check for any unsafe acts / conditions and, if observed, they will ask the relevant subcontractor / workers to take immediate corrective actions. The Contractor HSE Team shall also monitor the daily safety inspection activities and ensure that they are carried out responsibly by a designated person. 6.5 SAFETY CONTROL MEASURES (1) Crane and Heavy Equipment Control 1. Prior to mobilization of plant, a dry, firm, and level working platform shall be installed that is suitable for the safe operation of all plant and equipment. The designated working areas will be inspected by an appointed person, such as a safety Engineer. 2. All unloading, installation of plant and equipment and erection of cranes will be supervised by experienced and trained personnel. 3. Crane operators, rig machine operator and heavy equipment drivers shall be thoroughly checked whether they are in possession of current and valid licenses and/or competence certificates. 4. Handling and hoisting of heavy items with cranes will be coordinated by an experienced foreman with the help of safety supervisor or lifting supervisors. 5. All chains, hooks, slings, shackles and other equipment on a lifting device used for raising or lowering will be of Employer approved type and maintained in good condition. (2) Electrical Works Electrical installations and appliances used will meet applicable National Electrical Codes/standards. All electrical devices utilized by the Contractor or his subcontractors on this project will be equipped with and utilize ground fault circuit interrupter (GFCI) protected outlets or extension cord sets. HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land (3) Fire Fighting Equipment and Fire Prevention Adequate numbers of suitable types of portable fire extinguishers and/or other means (fire hose) to extinguish the possible fire shall be available on site at appropriate locations. 6.6 ENVIRONMENTAL CONTROL MEASURES (1) Water Pollution Control 1. Do not discharge water from dewatering operations directly into any live or intermittent stream, channel, wetlands, surface water or any storm sewer. Water from dewatering operations will be treated by filtration, settling basins, or other approved method to reduce the amount of sediment contained in the water to allowable levels. 2. Sedimentation basins will be configured so as to provide sufficient time for the suspended solids to settle out. 3. Stockpiles of construction materials on site will be covered with tarpaulins or similar fabric to prevent surface erosion. Contractor will minimize stockpiling of materials to minimize the chance of silt laden surface runoff. (2) Protection of Air Quality 1. The excavation working area will be minimized to the extent practicable to minimize odor emission potential. 3. Following the filling of storage facilities with odorous excavated materials, these will be removed from site. 4. Odorous materials will not be stored on the streets or in open areas. Temporary stored odorous materials will be maintained in a moist state or covered to prevent odor emissions (by water or watertight tarpaulins). (3) Noise Control Employees must be protected from the exposure of unacceptable level of noise generated by the bored pile activity, as it can be the cause of hearing loss of the workers and other serious diseases such as high blood pressure etc. In case of using machine and equipment generator providing power for the site, it is must to choose appropriate machines which do not produce bad effects from big noise to surrounded areas. Make every effort to minimize noises caused by the construction operations including: 1. Adopting good equipment maintenance and ensuring that the appropriate unit is chosen for each construction task; 2. Units not in use will be switched off; 3. Provide silencing of noisy equipment, particularly diesel-engine plants; HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land (4) Others Sewage is discharged into manhole to deposit mud, soil before discharging into the general sewer in the area. Vehicles transporting soil, materials shall be covered with canvas when circulating on the road. Spoil and scrap materials shall be discharged at stipulated places. The site shall be frequently cleaned, using water truck to spray water and clean the road in the construction area It’s not allowed to let Bentonite solution spilling out on surrounding area during the construction. Temporary area shall be clean and removed immediately after the project is handed over. At the entrance of the site, the contractor shall allocate 02 high pressure pumps and water reservoir to ensure that all vehicles entering into and out the site are clearly washed. The contractor uses soil container made from steel for each construction line. Bored pile machine after removing soil from boring pit, it will pour removed soil directly into the soil container. Humus soil from the container will be scooped up onto transportation means, removed out of the site and bulked at stipulated area. The contractor shall get permits from relevant authorities for continuous transportation of soil during the day. The contractor shall engage with environmental management company to arrange 01 water tank for washing the roads surrounding the site every morning (if necessary). Wasted Bentonite slurry will be periodically pumped, removed out of the site by specialist vehicles and assembled at disposal area. Enclosed: - Attachment #1 – Risk Assessment For Safety And Environmental Issues. HCMC Metro Cp-2 Project TITLE : MERGENCY RESPONSE CHART Utility Company Project POWER CO SAWACO CII TMUN Telephone Manager MAUR Report 7 Method Statement of Bored Pile Construction On Land Report Deputy (If necessary) Police: (08) 113 Fire: (08) 114 Ambulance: (08) 115 Accident (River):(08)3836. 8196 (in case of utmost urgency) Report (in case of urgency) Report Instruction Manager (in case of urgency) Report / Instruction Call Report (in case of utmost urgency) Construction Hospital Thu Duc Hospital: District 9 Hospital: Columbia Asia Hospital: No.175 Hospital: Report Instruction Project Manager Emergency Call No. NJPT Site Manager Instruction Report Report Site Engineer ACCIDENT / INCIDENT Subcontracto r [...]...HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land c) Bentonite Slurry Mix Design Basic function of bentonite is to act as a stabilizing agent for the bored hole In soil with high clay content, the bentonite slurry becomes very thick during excavation due to the suspended clay particles The thick slurry becomes difficult to pump for desanding To avoid this problem,... at all depths Piles shall not be bored so close to the piles, which have been casted not long ago with workable or unset concrete The piling may disturb the fresh concrete in the neighboring piles Boring and excavation for a pile shall only be commenced 24 hours after completion of any pile within a radius of 6.0m, center to center, and only after the concrete strength of the neighboring pile reaches... Bending Machine 11 Air Compressor 12 Tremie Pipe Remarks or For excavation of bored hole For handling of steel cages and concreting works For casting bored pile For fabricating rebar cages For fabricating rebar cages For airlifting (Cleaning) 80m For cleaning borehole HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land 13 Drilling Bucket D = 1000~1500mm Boring tools 14... bentonite slurry 6 m3 For bored pile casting Total Station / Auto Level Setting center point and elevation pile For measuring depth of borehole For containing excavated material and disposal bentonite For preparation work and support work * The equipment (type and quantity) might be changed depending on the site situation HCMC Metro Cp-2 Project TITLE : 3.2 Method Statement of Bored Pile Construction On... done following the submitted Site Safety Plan and Site Environmental Plan 6.1 HSE TRAINING HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land All workers who are to be engaged in Bored pile works shall be inducted and instructed by a competent person from the Contractor on safe methods of work, such as basic first aid training, safe use of cranes, slinging techniques,... Slump for pile boring ≥ 180mm 10 Pile eccentricity at C.O.L ≤100mm 12 Remarks Less than 1.10 g/ml 5 11 5.4 1.4-10 N/m2 or 4-40N/m2 9.5-12 Test method than or Tremie pipe depth under ≥2.0 m concrete Removing height at top ≥500 mm concrete INSPECTION AND TEST PERSONNEL During bored pile construction, inspection and test are performed by the QA/QC engineer and laboratory’s technician HCMC Metro Cp-2... which is separated apart from the bentonite pit HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land The sequence of cleaning work for the bottom of hole is as below: - Using cleaning bucket to remove lumps of clay, coarse sand and gravels at the bottom of the borehole Then, - Using reverse circulation method or air lifting method for replacing sedimentation of slime with... stability of pile head and degree of accuracy of pile center After removal of temporary casing, from 1 hour to 2 hours, the bored hole will be filled by soil and/or sand 2 RESOURCES TO BE USED 3.1 EQUIPMENT TO BE USED For the successful implementation of bored piling works, the following equipment will be mobilized The list of equipment for a typical working party is shown below Bored pile works will... Bentonite Slurry HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land e) Drilling works Temporary casings shall be free from any significant distortion They shall be of uniform cross- section throughout each continuous length During concreting, they shall be free from internal projections and encrusted concrete which might disturb the proper formation of piles From the... sonic tubs and core tube will be poured with water and covered on the top of tubes prior to casting concrete HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land Fig.10 Installation of the rebar cage (8) Setting of Tremie Pipe and Re-cleaning (2nd Time Clearing) of Bored hole a) Setting of Tremie Pipe Tremie pipes of dia 8-10 inches shall be used The tremie pipes with standard ... 9, Ho Chi Minh City GENERAL The objective of this method statement is to describe the construction methodology and procedure for bored pile work on land of HCMC Metro Project The bored pile construction... reinforcement to the bored hole Hanging the rebar cage at the designed level HCMC Metro Cp-2 Project TITLE : Method Statement of Bored Pile Construction On Land Stage Stage 1.Concreting of bored pile 2.Pumping... the bored piles will be taken place Bored piles with different diameters and lengths will be constructed in accordance with the construction working drawings HCMC Metro Cp-2 Project TITLE : Method