A COMPUTER PACKAGE ON INTERPRETATION OF PILE LOAD TEST DATA

Abstract

The ultimate capacity of piles is estimated using static analysis, dynamic analysis and load tests. However, it is settlement rather than capacity which governs the design load. The first two methods give only pile capacity. The load-settlement behaviour of the pile can be obtained from a load test. But they are expensive and the results are valid only for the particular pile and site conditions. Also, the ground conditions which prevail at the time of load test may not remain the same subsequent to load tests due to change in the moisture content in the top layers, thixotropic hardening, etc. Under these circumstances, the pile capacity cannot be directly estimated from the load-settlement curve obtained from load curve. So there is a need to develop a procedure for estimating load-settlement behaviour which takes into account the changes that may occur in the ground subsequent to load tests. One of the procedure to obtain the above objective is given by Coyle and Reese(1966). A computer program is developed using this method given by Coyle and Reese(1966) with modifiactions suggested by Vijayvergiya(1971) and Hazarika and Ramasamy(2000). The program is capable of taking into account the different site conditions. It can be run on a personal computer. Making use of the package, results are obtained to bring out the following 1. Effect of number of segments on the computed values. 2. Comparison of elastic compression of pile and total pile head settlement. 3. Effect of pile diameter on load-settlement behaviour. 4. Effect of pile length on load-settlement behaviour. Based on the results obtained it is found that the change in number of segments does not affect the result significantly. The increase in diameter rather than the increase in length has a greater influence on the load-settlement behaviour of a point bearing pile. A iii procedure has been outlined to moderate the result of a load test to obtain the • load-settlement curves for pile-soil condition different from test conditions