(o)-1 bored pile

HCMC Metro Cp-2 Project Doc.No:HCMC-ICR-

CM-BP-001

Rev. Date:3 Sep.2012

Rev.No : A

Page : 1 of 16

TITLE :

BORED PILE CONSTRUCTION IN WATER

PROJECT TITLE:

Ho Chi Minh City Urban Railway Construction Project

Ben Thanh - Suoi Tien Section (Line 1)

Construction Package 2 : Civil(Elevated & Depot)

(o) Preliminary Construction Methology and Temporary Work Requirement

1. BORED PILE CONSTRUCTION IN WATER

REVISION STATUS

REV. No. DATE DESCRIPTION REMARKS

A 3rd Sep. 2012 FIRST ISSUE

PREPARED BY CHECKED BY APPROVED BY

NAME H.W. Jung S.H. Jun Kazuomi Ikeshoji

SIGNATURE

DATE 3rd Sep. 2012 5th Sep. 2012 5th Sep. 2012

HCMC Metro Cp-2 Project Doc.No:HCMC-ICR-CM-

BP-001

Rev.Date:3 Sep.2012

Rev.No : A

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CONTENT

1 INTRODUCTION………………………………………………………………………………………….

1.1 GENERAL……………………………………………………………………………………………

1.2 WORK SCOPE………………...……………………………………………………………………

1.3 SUBMITTALS ……………………………………………………………………………………….

2 CONSTRUCTION PROCEDURE…………….………………………………………………………….

2.1 WORK FLOW CHART……………………………………………………………………………..

2.2 WORK PROCEDURE………………………………………………………………………………

3 RESOURCES TO BE USED…………………………………………………………..…………….…...

3.1 EQUIPMENT TO BE USED………………………………………………………………………..

3.2 MATERIALS TO BE USED………………………………………………………………………..

3.2 LABOR TO BE DEPLOYED……………………………………………………………………….

4 QUALITY CONTROL…………………………………..………………………………………………….

4.1 QUALITY CONTROL………………………………………………………………………………..

4.2 MATERIAL CERTIFICATE………………………………………………………………………….

5 ENVIRONMENTAL CONTROL…………………………………………………………………………..

5.1 CONSTRUCTION SITE WATER POLLUTION CONTROL MEASURES……………………..

5.2 PROTECTION OF AIR QUALITY………………………………………………………………….

5.3 NOISE CONTROL ……………………………………………………………………………….

5.4 TRAFFIC MANAGEMENT ………………………………………………………….……………….

5.5 WATER QUALITY CONTROL ……………………………..………………………………………

6 SAFETY, HEALTH, EMERGENCY AND AREA SECURITY……………………………………………

6.1 WORK/STORAGE AND OFFICE AREA SECURITY……………………………………………

6.2 SERVICES…………………………………………………………………………………………..

6.3 TRAINING…………………………………………………………………………………………….

6.4 HEALTH AND SAFETY PLAN…………………………………………………………………….

6.5 ELECTRICAL INSTALLATIONS…………………………………………………………………..

6.6 SAFETY AND PROTECTIVE EQUIPMENT……………………………………………………..


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Rev.No : A

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1 INTRODUCTION

1.1 GENERAL

The objective of this method statement is to describe the construction methodology and procedure for bored pile works by using earth-drilling machine. The sizes of the piles to be covered by this method statement are diameter 1500mm and those piles are located in water. The site management control was included in this methodology.

1.2 WORK SCOPE This method statement includes the following work scopes.

1.0) Cast-in-place concrete pile , Pile Diameter =1000mm ,1200mm , 1500mm 2.0) Sonic test

1.3 SUBMITTALS

Prior to commencement of the work, documents listed in the Construction specifications will be submitted as another document. Designated areas for the works are shown in lay out plan.


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2 CONSTRUCTION PROCEDURE

2.1 WORK FLOW-CHART

The sequence of works for bored pile in water is shown by the following flow-charts.

Checking of the casing :-Center point -Verticality

Checking bentonite properties and the depth of borehole

Checking:

- Concrete slump and

temperature

-Top level of concrete

Examination of the top level of the rebar cage

Controlling the bentonite slurry, toe level and the soil stratum (if necessary)

Checking bentonite properties and the depth of borehole

2. Survey Center Point

3. Setting of the temporary casing

4. Install drilling machine

5. Drilling work

6. 1st Cleaning of hole bottom

8. Rebar cage Installation

10. Bored pile concreting

11. Ultra-sonic (for all bored piles) Coring test (if any)

7. Koden test

9. Setting of tremie pipe & 2nd cleaning

12. Grouting of Sonic pipes

1. Working platform construction


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2.2 WORK PROCEDURE

The work procedure is described as follows.

(1) Working platform works Prior to the commencement of the bored pile works, working platform shall be constructed following working drawing. The elements of working platform shall be firmly assembled to ensure safety during construction.

(2) Survey the center point of the bored piles.

This will be set out by the total station survey equipment. The offset marking shall be prepared at least in two directions at least 2 meters away from the center of the bored pile location. Guide frame shall be installed to maintain correct position of piles.

(3) Setting of the temporary casing

The temporary casing will be installed by vibro hammer and the length of casing shall be considered and justified base on the soil condition. In installation of temporary casing, center point, verticality, stability shall be checked carefully against the allowable tolerance and non-movement during drilling. The top level shall be set following working drawing. Inner diameter of casing pipe shall be little larger at least 5 to 10 cm than bore hole diameter.

Guide Frame

Working Platform


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(4) Install drilling machine

Earth Drill machine shall be assembled on casing by crane and calibrated by an expert.

(5) Drilling works The pile length shall be designed by the Designer after consideration of test pile results. During drilling excavation of borehole, the bore hole will be protected from collapse by the provision of using bentonite slurry and temporary steel pipe casing. Prior to drilling works, the stabilization liquid as the bentonite suspension shall be prepared and tested to meet the criteria Bentonite will be mixed thoroughly with clean fresh water to make a suspension which will maintain the stability of the pile excavation for the period necessary to place concrete and complete construction. Dry powder bentonite is mixed with clean water according to required ratio by high mixing machine and stored in the tanks on the platform which supply to bored hole. The density of freshly mixed bentonite suspension shall be measured daily as a check on the quality of the suspension being formed. If bentonite properties don’t match the requirements as above, the addition shall be requested. Bentonite shall be pumped into the borehole during drilling and continuously maintained more 2.0m higher than ground water level for prevention of hole collapses. The depth will be check every 30 minutes and the soil stratum shall be monitored and recorded carefully to check actual soil condition. Soil sample will be collected every layer change.

Earth Drilling Machine

Working Platform


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Fig.1 Earth Drilling

(6) 1st Cleaning bottom of hole

For the supply of fresh bentonite slurry, tank for fresh bentonite slurry shall be installed the position which is separated with the bentonite pit. After 30~60 minutes of drilling finish, the cleaning work for the bottom of hole shall be carried out by cleaning bucket prior to airlift system cleaning of borehole. The sedimentation of slime or slurry in the hole shall be replaced with good slurry. After cleaning by cleaning bucket and airlift system, the depth of hole shall be measured to the designed level by measuring tape connected to a plump bob. Measuring of hole shall be carried out on the center and at four corner of the hole.

(7) Koden test

After remove Earth Drilling machine, Koden test will be carried out by an expert. Koden test result will be concluded by the expert and confirmed by the Employer’s Representative. Koden test result shall be attached in Document for Acceptance.

(8) Installation of the rebar cage

Each piece of the steel rebar cage should be fabricated and assembled according to the approved working drawings. U bolts will be use for splicing of rebar cage . Rebar cage and splicing shall be checked based on approved working drawing and inspection sheet. Additional reinforcing ring, diameter 25 mm will be used for hanging of rebar cage section and for the cage stabilized against distortion.


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The installation of ultra-sonic pipes and coring pipe will be fixed to rebar by additional bar and ties to the rebar cage. Top level of sonic pipes and coring pipe shall be equal top casing level then carefully checked to confirm the rigidity and tightness of pipes after installation; normally pipes are jointed by welded sleeve and capped at the top and bottom portion. After completion of fabrication for one rebar cage, it shall be carefully kept in dry and stable condition at stock-yard which is elevated about 20cm higher than ground surface. Condition of re-bar cage will be checked and cleaned constantly. If some soil or rust find remain on the re-bar cage, it will be remove all before installation of re-bar cage. After 1st cleaning is finished, the rebar cage shall be installed as soon as possible to prevent sedimentation and avoid the collapse of the borehole with slow speed & smoothly. When reached for the designed level, the rebar cage shall be suspended from the top of the casing by using additional hanger bar. The top level of the rebar cage shall be confirmed in comparisons with that of the casing.

Fig. 2 Installation of the rebar cage

(9) Setting of tremie pipe & 2nd cleaning

(a) Setting of tremie pipe

The tremie pipe segments will be connected by nipple and rubber gasket therein to watertight. These are lowered piece by piece until it reaches to the bottom of bored hole. When the tremie pipe reaches to the bottom of bored hole, it shall be lifted up for 200mm to 300mm in order to keep the enough clearance to discharge concrete. Tremie top will be connected with concreting hopper and fitted by a spongy ball.

(b) 2nd time cleaning of bore hole

Prior to placing concrete the depth of bored hole will be measured carefully once again. If slime or slurry sedimentation still remains, air-lift system will be used to take all slime out from the bottom of bored hole. The surging pipe (installed inside of tremie pipe) shall be moved around inside of the rebar cage. Before casting concrete, the depth and bentonite properties shall be carefully checked as requirement above.


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A measurement tape and plumb will be used for the re-confirmation of drilling depth and effect of cleaning work. The concrete placing shall be started as soon as possible after second cleaning of bottom of bored hole. And before casting concrete, it shall be confirmed by measurement tape that the sedimentation has been removed completely.

(10) Bored pile concreting

Prior to commencement of the concreting work, it will execute the following checking for prevention of blocking tremie pipe.

* Workability of concrete * Selection of the suitable tremie pipe (diameter, length per pipe and joint) * Check of leakage of pipe joints

The sonic pipes and coring pipe shall be filled of water and carefully covered to prevent from concrete falling therein. Concrete shall be continuously placed from pile toe to elevation which is minimum 0.8m higher than cut-off level by track directly or pumping machine through temporary bridge. Concreting shall be carried out in such a manner as to avoid interruption. The toe of the tremie shall generally be 2.0m to 5m lower than the concrete surface. A rubber spongy ball shall be placed within the tremie tube to prevent direct contact between the first charge of concrete and the water or bentonite. On first pouring, a 2m³ volume bucket filled with concrete will be set on the 2m³ hopper. Thus, a large volume of concrete will be poured into the borehole at one time. The purpose is to remove the sediments at the bottom, which is remaining after cleaning.

Fig. 3 Casting concrete

The schedule for casting concrete is confirmed in order to ensure concrete pouring continuously without interruption. Hence the top of concrete is contaminated by mixing with stabilization liquid therefore extra volume of concrete is to be used for confirmation of the clean concrete. The height of extra or surplus concrete is proposed to be minimum 0.8m from cut-off level; however this may be adjusted in consideration of site condition.


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Fig. 4 Casting concrete

Concrete pouring pipes are chocked on working platform and clean immediately after disconnecting to avoid obstruct concrete inside of the pipes. It is required to check the elevation of concrete on the bored holes by measuring tapes and plumb bob for adjusting the length of tremie pipe and control quality of bored pile, also to detect immediately any collapsing or narrowing of bored holes. The inspection sheet and calculation of concrete volume will compare to the diameter of the bore pile to determine if collapse or bored hole is narrow..

(11) Ultra-sonic testing and Coring test

After completion of construction for group of bored piles, the ultrasonic integrity test will be carried out by testing experts. In case of bad sonic test result, coring test will be carried out and countermeasure shall be proposed by Engineer.

Fig. 5 Pile test


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Fig. 6 Pile test


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3 RESOURCES TO BE USED

3.1 EQUIPMENT TO BE USED

The list of equipment for a typical working party is shown below. Several working parties will be provided to work at several locations simultaneously. The detail of machinery may differ for the each of working parties.

The List of Equipment for Work

Item Description Unit Q’ty Remarks

Drilling Machine Type D2000 Nos. 1 Drilling

Service crane 50T crawler crane

Nos. 1

Serve construction 100T crawler crane 1

Diesel Generator Type 350 kVA

Nos. 1

Electric supply Type 250 kVA 1

Vibro Hammer 240 KW Nos. 1 Install casing

Welding machine 150A Nos. 4 Welding rebar-cage

Cutting machine Nos. 2 Cutting rebar

Air Compressor 10 Kgf/cm2 Nos. 1 For Air Lifting

Tremie pipe D273mm,L=80m Nos. 1 For casting concrete

Casing Pipe D = 1500mm Nos. 6 -

Tank 30m3 Nos. 4

For Bentonite slurry 60m3 Nos. 2

Concrete Pumping machine

Nos. 1 For pumping of concrete

Water pump 30m3/h Nos. 1 For pumping clean water

Theodolite Nos. 1 For survey & checking of

pile location

Concrete Hopper 2 m3 Nos. 1

Bentonite Testing Equipment

set 1 For testing of bentonite

slurry

Water Pump 300m3/h Nos. 1 Pumping bentonite

Measuring tape Type 50m Nos. 2 Measuring depth

Surging pipe Type D140mm,

L=80m Nos. 1 Surging


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3.2 LABOR TO BE DEPLOYED Labors and/or trades to be deployed for Bored pile Work are listed below.

No. Work Description

Job Classification

Detail Manpower Remarks

1

General

Site Manager 1

2 Supervisor 1

3 Specialist 1

4 Engineer 1

5 Drilling Work Operator

Drilling Machine

1 Day and Night

6 Reinforcement Fabrication

Skilled Labor 14 Day and Night

Foreman 2 Day and Night

Electrician 2 Day and Night

Welder 2 Day and Night

4 QUALITY CONTROL

4.1 QUALITY CONTROL

All materials shall comply with all requirements in the specification and the samples shall be taken and checked under the Employer’s Representative supervision before using. The material quality which not matches the requirement shall be rejected. The approved material resource shall be used during project. The sample from new resource shall be taken and tested for the Employer’s Representative approval following the specification if the resource thereof is changed.

4.2 MATERIAL CERTIFICATION

Main material used in the permanent works shall be approved before commencement of work. Materials are as follows.

No. Description Relevant Specification Remark

1 Concrete Construction Spec.

2 Reinforcing Bar Construction Spec.

5. OCCUPATIONAL HEALTH AND SAFETY CONTROL

5.1 CONSTRUCTION SITE WATER POLLUTION CONTROL MEASURES

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 shall be treated by filtration, settling basins, or other approved method to reduce the amount of sediment contained in the water to allowable levels.


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2. Excavated soil, sediments and bad bentonite shall be kept in the separate tank and removed to approved dumping ground by barges (300m3).

3. The drainage channels shall be connected to sand or silt traps and sediment basins. Sedimentation basins shall be configured so as to provide sufficient time for the suspended solids to settle out.

4. Stockpiles of construction materials on site shall be covered with tarpaulins or similar fabric to prevent surface erosion. Contractor shall minimize stockpiling of materials in the wet season to minimize the chance of silt laden surface runoff.

5. Provide sufficient portable chemical toilets or other temporary toilets at all work sites. 6. The Consortium shall incorporate the above pollution control measures into a site

environmental management plan, taking into account of the actual construction me thods.

5.2 PROTECTION OF AIR QUALITY

1. Burning - The use of burning at the project site for the disposal of refuse and debris shall not be permitted.

2. The excavation working area shall be minimized to the extent practicable to minimize odor emission potential;

3. Following the filling of storage facilities with odorous excavated materials, these shall be removed from site immediately);

4. Odorous materials shall not be stored on the river banks, streets or in open areas; 5. Temporary stored odorous materials shall be maintained in a moist state or covered to

prevent odor emissions (by water or watertight tarpaulins); 6. Road transport of sediment shall be in covered watertight trucks; 7. Contractor shall appropriately route transport vehicles avoiding densely populated areas

as far as practicable; and develop appropriate environmental monitoring and action plans.

5.3 NOISE CONTROL

Workers have to be protected from the noise, as it can be the cause of lessening hearing of the workers. In case of using machine and equipment 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. Use of purpose-built noise barriers (fixed and mobile), if appropriate; 2. Adopting good equipment maintenance and ensuring that the appropriate unit is chosen

for each construction task; 3. Units not in use shall be switched off; 4. Provide silencing of noisy equipment, particularly diesel-engine plants;

5.4 TRAFFIC MANAGEMENT

Traffic Management Plan on river shall be controlled by River Management Station according to approved “Waterway Safety Solutions in period of Viaduct (Ch. 2+465 ~ 4+731), Saigong Bridge and Rach Chick Bridge Construction”. Concrete trucks coming and going out construction site shall be instructed by traffic controller and signal light system.

5.5 WATER QUALITY CONTROL

Water quality is defined and presented in TCVN 5942:1995 and TCVN 5944:1995, , it has a big relation to the execution process and must been abided by during construction. It must to take the pollutants out of polluted water before transporting to public wastewater treatment. The waste must be gathered and sent logically and regularly out of the site. Do not transport directly the waste from maintaining vehicles like oil, antipyretic liquid into the


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public wastewater treatment. 6. SAFETY, HEALTH, EMERGENCY AND AREA SECURITY

6.1 WORK/STORAGE AND OFFICE AREA SECURITY

The Consortium shall provide all labor, materials, equipment and supervision to provide security using both stationary and mobile patrols at the site. Investigate and write reports of security and fire related incidents Maintain security records for the site. Report to the safety Engineer on all security matters. All security personnel shall wear standard industrial security uniforms, of similar design and markings, clean and neat in appearance.

6.2 SERVICES

A. Project-wide Services The Consortium shall provide all of the following services at the work/storage and office area sites throughout the duration of the contract. a. The Consortium shall provide services of Guards 24 hours per day b. Each security employee must remain on duty until relieved by the successive shift. No

disruption of service will be permitted for meal breaks or other breaks during shifts. c. At least one security supervisor shall be on duty during each shift. Security guards shall

be provided as necessary to maintain security over the complete project site. Consortium shall provide all necessary security personnel as may be required by day and by night at weekends and any public holidays.

B. General Duties The Consortium’s security personnel shall: a. Observe and control access to the site as directed by site engineers b. Monitor vehicle-parking areas to deter theft and vandalism. c. Shall provide a continuous fire watch for the complete project site. d. Perform first line fire fighting to the limit of training and equipment available. e. Enforce a system for the identification of project personnel, visitor and vehicle control. f. Assist any person reporting injury, fire and emergency. Report emergency situations to

management of the Consortium the Employer’s Representative , local Fire and/or Police departments and escort emergency vehicles to the area of the incident.

6.3 TRAINING

At least one person who has been trained and certified in First Aid and CPR by the Red Cross of Ho Chi Minh City, or an equivalent organization, shall be present on-site during all project operations. Develop a training sequence to inform visitors of the hazards associated with the site and to explain emergency procedures. Provide a site-specific training session for personnel scheduled to work on-site. This training shall include a health and safety briefing on the following information:

1. Names of personnel and alternates responsible for site safety and health. 2. The hazards contractor expects to encounter at the site. 3. Work practices by which the employee can minimize risks from hazards.

6.4 HEALTH AND SAFETY PLAN


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The Subcontractor’s Health and Safety Program shall address accident prevention and methods of avoiding physical hazards present at the site.

6.5 ELECTRICAL INSTALLATIONS Electrical installations and appliances used shall meet applicable National Electrical Code standards. All electrical devices utilized by the Consortium or his subcontractors on this project shall be grounded or equipped with and utilize ground fault circuit interrupter (GFCI) protected outlets or extension cord sets. Electrical devices used in spaces that may contain flammable vapors shall be explosion proof.

6.6 SAFETY AND PROTECTIVE EQUIPMENT

1 All safety helmets, industrial safety and waterproof boots, gloves, harnesses, waterproof coats and hats, protective apparel and other necessary safety devices shall be provided by the Consortium for his employees and in compliance with local regulations and good safety practice.

2 The Contractor shall provide such items of protection and apparel in sufficient quantities for use by the Employer’s Representative and his employees, representatives and subcontractors on site, together with a number of safety helmets and industrial safety and waterproof boots of varying sizes and umbrellas for use by official visitors.

(o)-1 bored pile

Documents

bored pile construction

construction procedure

construction methodology

construction package

construction specifications

water project title

water quality control

work procedure