Cyclic Degradation of a Multidirectionally Laterally Loaded Rigid Single Pile Model in Compacted Clay

In practice, the lateral loads applied to piles are often multidirectional. To examine the effect of the loading path on the behavior of piles embedded in clay under lateral cyclic loading, a series of model tests under various displacement paths was conducted using a computer-controlled biaxial motion platform. The displacement paths at the pile head were the unidirectional regular path, the cross path, the eight-shape path, the unidirectional irregular path, and the multidirectional irregular path. The experimental results revealed that under the same displacement amplitude, degradation of the lateral resistance with the number of cycles was more significant under the eight-shape path than under the cross path, and the degradation under the cross path was more significant than under the unidirectional path. The degradation factor was as high as 38% under the eight-shape path with a relatively large displacement amplitude, which was approximately 65% larger than the corresponding value under the unidirectional path. The results for the irregular paths also indicated that the resistances under multidirectional loading were lower than those under unidirectional loading.