Cyclic axial loading analysis of piles in sand

This paper develops an analysis for the behavior of a single pile or symmetrical pile group in sand under cyclic axial loading. The analysis allows consideration of the effects of degradation of skin friction, base resistance and soil modulus, the influence of loading rate, and the accumulation of permanent displacements. Laboratory data for skin friction degradation are presented and it is shown that the amount of degradation due to cyclic loading depends on the cyclic displacement, the number of cycles, the soil type, and the type of pile. Theoretical solutions for a hypothetical pile and a recent field test emphasize the importance of determining whether the degradation of skin friction depends on the absolute cyclic displacement or the cyclic displacement relative to the pile diameter.