Sabtu, 26 Mei 2012

METHOD STATEMENT FOR KENTLEDGE MAINTAIN LOAD TEST




I would like to share my experience in testing of piles during construction. The common test which 
implemented at site in order to check the performance of piles is kentledge Load Test / Static Load Test.  

The main objective of the load test is to study the performed working barrette piles when the 2 time
working load apply to the selected tested pile.

The performance of the test pile shall be deemed to have satisfied the requirement of the specification , if the settlement /deflection of the  pile head at various stage of loading in Maintained Load test complies with the specification requirement given below:

1)   When residual settlement after removal of test load shall not exceed 6.50mm

2)   When total settlement under working load shall not exceed 12.50mm or 10 % of the pile diameter, whichever is lower value

3)   When total settlement under twice working load shall not exceed 38.0mm or 10% of pile diameter, whichever is lower value.


1.0  SCOPE

The test is applied by means of a jack, which obtains its reaction from a property stacked kentledge comprising precast concrete blocks. The total weight of the kentledge shall be greater than the required test load and shall be placed on a platform supported well clear of the test pile.

This Method Statement will cover the full pile static load test procedure as detailed in the following test stages:
§  Pile preparation after completion of driving
§  Installation of jack, load frame and kentledge
§  Incremental loading and the monitoring of displacement
§  Assessment of settlement figures
§  Quality assurance and quality control
§  Associated items (safety and environmental management)




 
2.0              CONSTRUCTION PROCEDURE
2.1              Pile Preparation After Completion of Driving
After the test pile has been driven to set, it will be left for 5 days before placing of the static load. During this time, the pile head will be trimmed or the surrounding ground level reduced to allow the pile head to project. The pile head will be thoroughly cleaned and capped with non-shrink grout to ensure a firm bearing surface perpendicular to the pile axis.

2.2              Installation of Jack, Load Frame and Kentledge
The hydraulic jack is placed onto the pile head with a steel packer plate between the jack and the pile head. The ram of the jack should be adjusted until it is projecting. The settlement monitoring frame is next mounted to the pile head- this frame will be made of steel channels tied together around the pile head with two tie rods and bolts as detailed in Sketch SLT 1 below. 4 ‘reaction’ legs (steel tube) are driven into the ground adjacent to the ends of the channels and a concrete plug placed around each leg for additional stability. These legs will have small steel plates welded horizontally to the top once installed. The settlement gauges will be fitted to the ends of the channels and the gauge measurement arm will rest against the individual leg. Settlement gauges will only be installed after the load frame and kentledge have been placed, as described below.

The load frame can now be installed directly over the jack with the jacking beam set higher than the ram. The load frame will be supported on the outside by two lines of concrete blocks as detailed in Sketch SLT 1 below. The kentledge blocks are now loaded individually onto the frame using a crane – this should be done to ensure that the load is evenly distributed at all time i.e. the entire frame is laoded with the first layer of concrete blocks before the second layer is started, the second layer is finished before the third layer is started, etc. This will ensure that the kentledge load is stable at all times and will allow safe access for all personnel. This loading procedure will continue until the entire kentledge has been installed.


Once completed, the kentledge should be left for a settling period of 24 hours. The 4 settlement gauges are next installed at each end of the channels with their measurement arms projecting vertically downwards.

 This measuring arm shall rest against a plate of glass resting on top of the steel leg. Any gap between the jack ram and the bearing plate at the base of the jacking beam should first be closed with a steel packing plate – this will ensure that there is still sufficient stroke in the ram to load the pile to the full test load. The jack ram is now extended to the point where the load gauge starts to rise – each settlement gauge is zeroed, the reading recorded and the static load test can be commenced.

2.3              Incremental Loading and the Monitoring of Displacement
The pile is now loaded according to the incremental sustained load test method as defined by the Designer.

A datum should be established on a permanent object or other well founded structure which shall not be disturbed by the test loading or other operation on the site.

The entire test area must be sheltered from direct sunlight, wind, rain and be sufficiently lighted during the night to facilitate taking readings.

The monitoring of the displacement will be done by applying the jack load up to the specified load, immediately recording the settlement reading, re-recording the settlement (where appropriate) at specified time interval after reaching load and also immediately prior to any change in load. The same procedure would be followed for the next load state.

Once the test has been completed, the jack ram will be withdrawn and the load frame with kentledge will be removed.

Maintained load test results shall be recorded for further analysis by consultant

2.4              Assessment of Settlement Figures
Before the removal of the kentledge and load frame, the settlements will be analyzed according to design requirement. Should the measured settlement figures be within the limits, the pile will be considered as having passed the maintained load test.

3.0              SAFETY
5.1       General Safety
The Site Manager, will have overall responsibility for safety.

As the construction area will be isolated and fenced, the danger of injury to members of the general public is minimal. All site visitors within the construction areas will be accompanied by a member of the Site Team.

The following general safety issues will be addressed on site:
§    All lifting appliances and lifting gear shall be inspected by a competent person (e.g. by a LCM Safety Officer or suitably experienced Plant Manager) and certified as having adequate capacity for their intended purpose.
§    All lifting gear should be regularly inspected for damage that effect capacity.
§    Lifting appliances shall only operate on a firm base of adequate bearing capacity.

5.2  Personnel Safety
All new workers and staff will attend the Safety Induction Course before commencing on site work.

All personnel will wear safety helmet and safety boots. Eye protection shall be worn by all welders.

All workers must attend the weekly toolbox meetings held on site.

Any unsafe acts or conditions to be identified and correctly promptly or referred to the respective supervisor. Any accident or incident to be reported immediately so preventive action can be taken to prevent re-occurrence.

5.3  Training
All staff members will be briefed on the importance of monitoring on site safety by the Safety Manager.

6        ENVIRONMENT
The Site Manager will have overall responsibility for the environment.

All new workers and staff will attend the Environmental Induction Course before commencing on site.

Typical environmental management measures will be monitored in accordance with the following documents:
·                     The Project Environmental Plan
·                     The Project Management Plan




  
 LOAD TEST TABLE EXAMPLE

1
1 ST CYCLE
Settlement At 140 Ton
=3.6750mm
2
1 ST CYCLE
Settlement At 0 Ton
=0.0125mm
3
2 ND CYCLE
Settlement At 280 Ton
= 9.2075mm
4
2 ND CYCLE
Settlement At 0 Ton
= 0.7300mm



DATE
TIME
LOAD ( TON )
SETTLE ( MM)
R1 (MM)
R2 ( MM)
16/3/05
2.00PM
0.00
0.000
100
100

4:00PM
35.0
0.7275
100.8
100

6:00PM
70.0
1.5275
101.5
100

8:00PM
105.0
2.3925
103.0
100
17/3/05
2:00AM
140.0
3.6750
102.5
100

3:00AM
105.0
3.2700
101.5
100

4:00AM
70.0
2.2675
101.0
100

5:00AM
35.0
1.3825
100.0
100

6:00AM
0.0
0.0125
100.5
100

8:00AM
35.0
0.4250
101.5
100

10:00AM
70.0
1.2225
102.0
100

1200AM
105.0
2.6225
102.0
100

2:00AM
140.0
3.5700
102.5
100

4:00PM
175.0
5.3625
104.0
100

6:00PM
210.0
5.7100
105.0
100

8:00PM
245.0
6.8000
107.0
100
18/3/05
8:00PM
280.0
9.2075
109.0
100

9:00PM
210.0
8.4525
108.5
100
19/3/05
10:00PM
140.0
7.1275
107.5
100

11:00PM
70.0
4.5075
104.5
100

12:00PM
0.0
0.7300
101.0
100








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