Work Method Statement for Test Pile

WORKS METHOD STATEMENT

PRELIMINARY TEST PILE



APPROVAL






REVISIONS RECORD

REV. DATE ISSUED REVISION DESCRIPTION APPROVAL STATUS
0 04/04/03 FIRST ISSUE FOR APPROVAL
1 23/04/03 SECOND ISSUE FOR APPROVAL – Incorporate with the comments






TABLE OF CONTENTS


1.0 INTRODUCTION
2.0 DESIGN CONSTRAINTS AND COORDINATION
3.0 CONTRACTING METHODS
4.0 PROCUREMENT METHODS
5.0 RESOURCE PROVISIONS
6.0 LOGISTICS PROVISIONS
7.0 MATERIAL MANAGEMENT SYSTEMS
8.0 CONSTRUCTION METHODS AND TECHNOLOGY
9.0 CONSTRUCTION PHASING AND WORKFLOW
10.0 TRAFFIC MANAGEMENT AND MONITORING
11.0 SAFETY PROGRAMME
12.0 QUALITY ASSURANCE AND CONTROL PROGRAMMES
13.0 INDUSTRIAL RELATIONS POLICIES
14.0 ENVIRONMENTAL MONITORING PROGRAMMES
15.0 APPENDICES



1.0 INTRODUCTION

The main objective of the instrumented load test is to establish the following for the use in the design of working piles, which are to be constructed in soil strata having similar geological structure and by adopting similar construction practices:

i) To determine/confirm the bearing capacity of bored pile and its appointment into shaft friction and end bearing;
ii) To evaluate the design parameters in relation to the ultimate skin friction and end bearing; and
iii) To study the behaviour of pile settlement and structural shortening of pile under the applied loads.

With proper implementation of instrumentation (Strain Gauges and A-9 Retrievable Extensometer installed internally in bored piles in this case), the data collected from instrument load testing are able to produce reliable information for meaningful interpretation.

The load-movement relationship, the distribution of axial load along the pile and the load transfer characteristics of the pile will be presented and discussed in detailed in the test report at later stage. Results will be presented both in tabulated and graphical format for easy discussion.


2.0 DESIGN CONSTRAINTS AND COORDINATION

Not Applicable

3.0 CONTRACTING METHODS

The Conditions of Contract have been reviewed by PCSB and particularly those conditions in respect of Sub-contractors. The conditions are bespoke for this project and therefore are required to be reflected in any form of Sub-contract utilized on the project.

Please refer to PHOS-CN-010 to PHOS-CN-030 for the Contract Procedures.


4.0 PROCUREMENT METHODS

Since PCSB is liable for the performance of any Sub-contractor, it is vital that only companies with proven track records in the relevant activity will be engaged as Sub -contractors.

It is acknowledged that before any part of the works can be sublet, the approval of the Employer’s Representative is required.

Please refer to PHOS-PR-010 to PHOS-PR-030 for the procurement procedures.

5.0 RESOURCE PROVISIONS

5.1 Manpower/Labour

Please refer to the Project Organisation Chart.

5.2 Plant Equipment

The following equipment shall be used during the test pile works:
• Vibrating Wire Load Cell
• Vibrating Wire Strain Gauge
• Dial Gauges (11 Numbers)
• Pressure Gauges (2 Numbers)

The Calibration Reports are attached in Appendix 15.5.


6.0 LOGISTICS PROVISIONS

The logistic control shall be in accordance with the approved Site Logistic Plan.


7.0 MATERIAL MANAGEMENT SYSTEMS

Please refer to PHOS-CP-040 for the Material Control Procedure.


8.0 CONSTRUCTION METHODS AND TECHNOLOGY

8.1 Test Pile Instrumentation and Proposed Method of Installation

The instrumentation specialist is :

Spectest Sdn Bhd
No. 20, Jalan Desa Serdang 4,
43300 Serdang Lama,
Selangor Darul Ehsan

For the instrumented test pile, two types of instruments, namely, the Vibrating Wire Strain Gauges (VWSG) and A-9 Retrievable Extensometer were specified to be installed internally in the test pile to monitor the strain development and structural shortening behavior of the pile during load testing.



i) Vibrating Wire Strain Gauges:

Model VSM-4000 Vibrating Wire Strain Gauges (VWSGs) manufactured by GEOKON, USA :

The gauges are specified to be installed at levels (level A to H) with 4 numbers per levels for 800 diameter test pile.

The VWSG at those levels will be designated as :
A1, A2, A3 & A4 at level A;
B1, B2, B3 & B4 at level B;
C1, C2, C3 & C4 at level C;
D1, D2, D3 & D4 at level D;
E1, E2, E3 & E4 at level E;
F1, F2, F3 & F4 at level F;
G1, G2, G3 & G4 at level G;
H1, H2, H3 & H4 at level H accordingly;

The strain gauges are manufactured by Geokon, USA and are of the compressive-range type. The principle of measuring strain by VWSG is based on the fact that the frequency of vibration of the taut wire, restrained at both ends, varies with the square root of the tension in the wire. Any change of strain in the structural steel member to which the gauge is mounted is indicated by a change of tension in the wire.

In the test pile, each strain gauge will be mounted to two endblocks, which were arc-welded to the main reinforcement bar at the designated level. The signal cables from the pick-up sensors tightened to the strain gauges were led along the reinforcement bars with strong ties to the top of the piles, terminated in a junction box and monitored using a Geokon Liquid Crystal Display (LCD) Indicator. The latter registers readings in micro-strain.

The technical information on VWSGs and the Indicator, detail description of VWSGs, method of gauges installation and taking reading are given in Appendix 15.1.

ii) A-9 Vibrating Wire Retrievable Extensometer:

A pair of steel pipes with nominal diameter of 52mm shall be cast in a pile. The displacement tranducer is attached to the anchor and spring loaded connecting rods, can be pre-assembled to the required level and then lowered into position. Prior of load test, the anchors need to be pressurized, so that the pistons are forced out against steel pipe wall and clamp firmly. Displacement measurement of each vibrating wire tranducer can be read by either by GK 403 readout or MICRO-10 DATALOGGER

The technical information, method of installation and monitoring are given in Appendix 15.2.

8.2 Load Distribution Computation (from Vibrating Wire Strain Gauges measurement from load test)

The load distribution will be computed from the measured changes in strain gauge reading and estimated pile properties (steel content, cross-section areas and modulii of elasticity.

Load transferred (P) at each level is generally calculated as follows:

P = e (Ec.Ac + Es.As)

Where
E = average change in strain gauge readings.
Ac = cross-sectional area of concrete
Ec = Young’s Modulus of Elasticity in concrete
As = cross-sectional area of steel reinforcement bars
Es = Young’s Modulus of Elasticity in steel = 200kN/mm2



9.0 CONSTRUCTION PHASING AND WORKFLOW

9.1 Loading Procedure

The proposed loading procedure for preliminary test pile is shown in Appendix 15.3.

9.2 Test Pile Arrangement and Position of Instrumentation

Please refer to Appendix 15.4 or the details on the test pile arrangement and the position of its instrumentation.

The debonding from ground level to cut-off level will be carried out by loosing the surrounding soil with boring method and refilling with loose soil.

The socketing length into rock for the reaction piles is now revised to 2.0m and the calculation revised accordingly.

The tendon bond length is revised to 5.0m and the calculation revised accordingly.

Additional stiffener plater are now added on the reaction beams are shown in drawing.

The anchors shall be properly seated on a plat surface and fastened to ensure effective axcessive movementr of the reaction systems. The two reaction beams shall be properly set-up to ensure that these beams act as a whole units during testing.


10.0 TRAFFIC MANAGEMENT AND MONITORING

The Logistic Manager shall be responsible for the management and control of the traffic in and out from the construction site.


11.0 SAFETY PROGRAMME

Please refer to PHOS-HS-010 Health and Safety Plan.


12.0 QUALITY ASSURANCE AND CONTROL PROGRAMMES

Not Applicable


13.0 INDUSTRIAL RELATIONS POLICIES

Not Applicable


14.0 ENVIRONMENTAL MONITORING PROGRAMMES

Please refer to PHOS-EMP-001 Environmental Management Plan


15.0 APPENDICES

15.1 Technical Information on Geokon Strain Gauges, Read Out Indicator, method of Gauges Installation and taking readings
15.2 Technical Information on Vibrating Wire Retrievable Extensometer, Method of Installation and taking reading
15.3 Proposed loading procedure for preliminary test pile
15.4 Details on the test pile arrangement and the position of its instrumentation
15.5 Calibration Reports