Load Testing of Piles

Load testing of piles consists of two categories. Initial load test is completed to determine the ultimate load carrying capacity and to arrive at the safe design load on the pile. It also helps to fix guidelines for routine tests, assess the suitability of the piling system, and to study the effect on existing adjacent structures etc. The second kind of test is the routine test to check whether the pile is capable of carrying the designed load. Such tests are commonly carried out on ½ to 2% of the total number of piles at the site that was intended for a test load of one and a half times the working load, maximum settlement shall not exceeding 12 mm.

Piles are loaded through jacking against a kentledge placed on a platform supported clear of the test pile or against a beam restrained through anchor piles. Settlements of the pile are recorded through dial gauges carried by supports clear of the pile and resting on arms fixed rigidly to the pile head.

There are two techniques of applying test loads. In the Constant Rate of Penetration (CRP) test, the load is adjusted to provide a constant rate of downward movement. In the ML (Maintained Load) method, the load is applied in increments and deflections recorded. The CRP test is suitable for determining the ultimate load, although the ML method could be used for both initial test and routine tests.