Calculation model for lateral response of piles considering the characteristics of sand convection under asymmetric cyclic loading

Pile foundations supporting wind turbines and offshore platforms are always subjected to asymmetric lateral cyclic loads from wind and waves. To calculate the lateral response of the pile in sand under asymmetric cyclic loading, this paper proposes a $p-y$ curve model to deal with different levels of load reversal. According to the state of the soil around the pile under asymmetric cyclic loading, the scaling factor of the reloading curve is modified. The soil collapse-recompression model is also extended to apply to different cases of asymmetric cyclic loading according to the characteristics of soil convection during asymmetric cyclic loading. By modifying the shape and position of the $p-y$ curves to different degrees, the lateral response of the pile under asymmetric cyclic loading can be obtained in combination with the improved finite difference method. The validity of the proposed model is demonstrated by comparing the results with the centrifuge model tests. Then, the pile displacement accumulation, the variation of the bending moment, and the soil resistance under asymmetric cyclic loading, are further discussed.