Analysis on Modification of the Measured Results of Test Pile Due to the Influence of Reaction Piles in Static Loading Test

摘要

In static load testing, the measured displacement of the test pile is different from that of an individual pile loaded by the same load. This is because the transferred load of the reaction piles through the soils causes an opposite movement of the test pile. To modify the measured results of test pile due to influence of reaction piles in static loading test conducted by using reaction piles as the reaction system, this paper presented a simple analytical approach for the analysis of the influence of reaction piles on the test pile response in static load testing. This was done by using the load-transfer approach. In this paper, the shaft displacement at a given depth was assumed to be composed of the pile-soil relative displacement developed at the disturbed soil around pile and the elastic vertical soil displacement developed in the soil mass. A load-transfer function which is similar to a hyperbolic model was then established to simulate the relationship between unit skin friction and shaft displacement at a given depth. Furthermore, a hyperbolic model was used to describe the relationship between unit end resistance and pile end displacement. Considering interactive effects between reaction piles and test pile, the load transfer function of the test pile in static load testing conducted using reaction piles as the reaction system is proposed. As to the analysis of the response of an influenced test pile considering progressive deformation of pile-soil system, a highly effective iterative computer program was developed to modify the response of an influenced test pile in static load testing. Comparisons of the load-settlement responses of a single pile and an influenced test pile in static load testing demonstrated that the proposed method is generally in good agreement with the observed behavior and the calculated results derived from other approaches.