The purpose of carrying out pile driving test is to confirm on the design bearing capacity, soil condition, design length of pile, construction period and applicability of construction equipment and the pile driving test shall always be carried out in the presence of the Engineer.
Therefore, the Contractor should carry out the loading test for the pile before proceeding series of piling. The method of loading test should be followed by Engineer’s directions. If it is not specified in the designing document, corresponding to each diameter, length, bearing capacity of pile from the quantity of trial piles must be more than 1% of pile quantity and minimum at least 2 piles.
STATIC LOAD TEST
Before proceeding series of piling, the Contractor must carry out the static loading test for the pile. The Contractor must establish the pile static loading test thesis and submit for the Engineer’s approval before implementing. The test must follow strictly the approved designing document. Its content must mention the followings:
- Features of construction
- Features of the ground at the constructing site and at the testing position
- Proceeding method
- Resting time of pile after completing proceeding until testing
- Trial capacity and greatest change of pile position as anticipated.
- Method and procedure for loading extending
- Anticipation on the time, progress of trial organizing.
- Requirements on testing equipment
- Other necessary requirements.
DYNAMIC LOAD TEST
Dynamic load testing shall be performed during pile driving work. Wave speed shall be measured for pile prior to setting up the pole for loading test. When measuring the wave speed, pile shall be laid down horizontally on flat ground, and measure shall be taken to prevent contact with other piles. Pile shall be driven down to the depth of reaching ultimate bearing capacity.
During driving of pile, the stress acting on pile shall be monitored and controlled to stay below the allowable value. When necessary, striking energy transmitted to pile shall be reduced to maintain the stress below the allowable value by adding cushion or by reducing the output hammer energy. After completion of dynamic loading test, the Contractor shall report the results to the Engineer for confirmation and shall determine the number of pile and driving depth for the Work.
When passed 24 hours from the completion of dynamic pile load testing, test instrument shall be attached to the pile and pile shall be re-driven. Penetration depth of pile during re-driving shall be less than 150mm, and the number of hammering shall be less than 50 times.