Pile Load Test – Methodology
Pile Load Test – Methodology
GENERAL
The testing of pile will be carried out according to the lndian Standard IS: 2911 (Part4)-1985.
In accordance with the relevant provision of the Indian Standard lS:2911 (Part 4) I985, the sate load on a single working pile in the load test shall be least of
Two- thirds of the final load at which the total displacement attains a value of 12 mm unless otherwise required in a given case on the basis of nature and type of structure in which case, the safe load should be corresponding to the stated total displacement permissible.
Routine Vertical Pile Load Test Step by Step
METHODOLOTY OF TEST
lt is proposed to conduct the load test on the test pile by the application of vertical compression loads on the pile top by means of a hydraulic jack reacting against a platform supporting the kentledge and the settlements will be recorded by suitable positioned dial gauges. Maintained — load method as detailed in the lndian Standard will be followed.
The load test will be carried for a maximum load at 1.5 times the design load.
PILE HEAD PREPARATION
The pile head will be chipped off carefully till sound concrete is met with. The projecting reinforcement bars will be cut off and the top finished smooth and level with plaster of paris so as to obtain a horizontal surface. On this prepared pile head a bearing plate will be placed to receive the jack base.
DESIGN OF PILES BASED ON LOAD CAPACITY
KENTLEDGE
The kentledge will consist of Concrete blocks stacked over a platform built up of rolled steel beams and plates resting over them.The platform will rest over steel crib / sleeper cribs / sand bag supports clear of the test pile.
The kentledge Weight will be about 1.10 times more than the load test,providing a margin over the maximum test load.Care will be taken in the placement of the kentledge on the platform in order to ensure that the center of gravity line of the total load mass is as far practicable,coaxial with the axis of the pile.
The platform will be of suitable size to accommodate the kentledge.
When And Where To Use Pile Foundation
SETLEMENT OBSERVATIONS
The load application and settlement observations will be made at the pile top.
Settlement will be recorded using four dial gauges with a least count of 0.01 mm and travel of 25 mm.The gauges will be positioned at an equal distance around the piles and will be held by datum bars resting on immovable supports at a minimum distance of 1.50 m from the peripheral edge of the pile.Typical load test set up is given
LOAD APPLICATION
The test load will be applied by means of a hydraulic jack of suitable capacity.The jacks will butt against the jacking girder assembly bearing against the loaded platform.The jacking grider assembly will consist of rolled steel beams/plated beams,with the bottom flanges well braced.
The test will be carried out by applying a series of vertical downward incremental loads,each increment being about 20% of the safe load on the pile.The pressure will be read from the pressure gauge attached to the hydraulic pump.At each stage of loading the actual gauge pressure multiplied by the total ram area of jack will be the applied load.
At each stage,the loading will be maintained till such time the rate of movement of pile head is not more than 0.1 mm in the first 30 minutes or 0.2 mm in the first one hour, or for maximum of 2 hours,if either of the earlier of the two earlier conditions is not fulfilled.
Time and settlement observations will be made at the commencement and completion of each stage of incremental loading.The settlement observations will also be continused at about 15 minute intervals during the period when the applied load is constant.
When the loading has reached the test load level,it will be maintained for a period of 24 hours.The loading will then be brought to zero gradually in stages by releasing the jacking pressure progressively.
Important Things to be Followed Driven Cast-In-Situ Piles
RECORDS
The load displacement and time will be recorded sequentially in a tabular form along with information about the test pile.A report will be prepared on the test analysing the test results and bringing out the conclusion.A load displacement curve will form an essential part of the presentation.
