Monday, April 7, 2008

Method Statement For Bored Piling Works

WORKS METHOD STATEMENT

BORED PILING WORKS




APPROVAL






REVISIONS RECORD

REV.
DATE ISSUED
REVISION DESCRIPTION
APPROVAL STATUS
0
31/03/03
FIRST ISSUE FOR APPROVAL














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

This Work Method Statement outlines the method of which the bored piling works are installed for the project.


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 be 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

The number of manpower/labour to be used during the earthworks activities have been identified in the Manpower Histogram.

5.2 Plant Equipment

Hydraulic bored piling plant shall be used. The piling plants consist of a telescopic kelly bar and the lower of the kelly bar is an adaptable to other drilling tools.
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 Piling

On completion of the temporary platform, the piling rigs shall be moved in assembled and ready for work on the installation of the 800 mm and 1050 mm diameter bored piles. A test pile for vertical pile shall be carried out to verify the designed load carrying capacity of the piles, the installation of which shall be determined jointly with Employer’s Representative.

8.2 Bored Piles

Bored piles are cast-in-situ piles formed by excavating a hole of the specified size (diameter), to the required depth and casting the excavated hole with concrete of specified strength after the reinforcement is lowered into the hole.

8.3 Positioning Of Boring Plant

The hydraulic pile points setting out shall be provided by a qualified Surveyor. The boring plant will be moved to the pile point intended for excavation. The kelly bar mounted with an auger is placed just above the pile point. The vertically of the kelly bar should be checked by means of a spirit level. Adjustment should be made so as to enable the kelly bar to be as vertical as possible. Then the positions of the auger is checked against the pile point.

Adjustment should be made so that the center of the auger is nearest to the pile point. The auger is then lowered and boring operating commenced.

Reasonable care should be taken so that the pile position and vertically are constructed within the specified tolerance i.e. 75mm and 1 in 150 respectively.

8.4 Boring

Boring commerce after the positions of the boring plant is checked. Usually, an auger of the required size is used to excavate hole is collapsible; a temporary casing of the same size should be installed to prevent collapse. Excavation of the hole continued until the required depth.

At the point of encountering the rock head level where soil drilling tools are unable to penetrate the strata any further, boring shall cease in order that the Employer’s Representative to verify the occurrence and confirm the rock head reduced level.

Rock drilling tools shall be used for drilling into and through rock.

After reaching the required depth, a cleaning bucket will be used to clean up the bottom of the borehole. A joint measurement of the depth should be made before lowering of reinforcement and concreting.

8.5 Reinforcement

Reinforcement to bored piles will be fabricated in the reinforcement yard and transported to the borehole for placing. After fabrication by the bar benders, the helical links will be tack welded to the main reinforcement Laps are also to be welded sufficiently so that they are intact during transportation. 100 mm diameter round spacers will be welded to the reinforcement to provide the cover to the reinforcement against the soil during concreting.

The reinforcement will be lowered to the completed bore hole, prior to concreting, by means of a service crane arid to be adjusted to the correct level.

8.6 Concreting

Concreting conforming to the specification will be delivered to the site by Ready Mixed supplier.

If bore hole are dry, the concrete shall be discharges through a short funnel at the top of the bored hole to prevent free falling concrete hitting the sides of the bore. If bored holes contain either water or bentonite drilling mud the concrete shall be placed by the tremie method.

(i) Dry Hole Mix

This mix shall be designed to give a works cube strength of 35 Mpa at 28days with a slump of 100 ± 25mm.

(ii) Tremix Mix

This mix shall be designed to give a minimum works cube strength of 35 Mpa at 28 days with a slump of 175 ± 25mm.

The method of placing shall be such as to ensure that the concrete in its final positions shall be dense and homogeneous.




The piles shall be concrete in one continuous operation immediately after the excavation has been completed and inspected where inspection is required by the Specification. If the continuity of placing the concrete is interrupted, no further concrete shall be placed without the prior approval of the Engineer.

8.7 Extraction Of Temporary Casing

All temporary casings are to be extracted immediately after completion of concreting. A vibro-Hammer will be used to extract the casing.

Reasonable care should be taken to ensure that the concrete level is above the cut-off level after extracting of casing point.


9.0 CONSTRUCTION PHASING AND WORKFLOW

Please refer to Appendix 15.3 for the bored piling works phasing and workflow.


10.0 TRAFFIC MANAGEMENT AND MONITORING

The Logistic Manager and the traffic management contractor 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

Please refer to Appendix 15.1 for the Inspection and Test Plan and Appendix 15.2 for the Piling Checklist.


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 Inspection and Test Plan – Bored Piling
15.2 Inspection Form – Bored Piling
15.3 Construction phases and workflow for bored piling works

2 comments:

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Chinnasamy Thangadurai said...

Thanks for your information sharing method. Really great. We are all(civil Engineers)must sharing our experience and good moral role to our Juniors,
Thanks a lot,
Regards,
durai