Discrete element simulation on the behavior of open-ended pipe pile under cyclic lateral loading

Abstract

The offshore pile foundations are subjected to lateral cyclic loadings such as winds, waves, and currents with complex force characteristics, which can cause complex structure responses. In this paper, the discrete element method (DEM) is used to carry out a numerical study on the force characteristics of open-ended pipe piles under lateral loading. The simulation results show that the pile rotates under cyclic loading, the centre of rotation is about 85% of the buried depth of the pile, and the cumulative angle of the pile is less than 0.1°. When a periodic load is applied, the soil around the pile is disturbed, resulting in plastic displacement, and the soil affected area around the pile forms a “butterfly shape”. The displacement in the “active zone” is larger than that in the “passive zone”. As the cycle time increases, the horizontal stiffness gradually decreases in the first 10 cycles, and the attenuation amplitude reaches more than 29% after 100 cycles. The reduction of the internal and external frictional resistance of the pile mainly occurred in the first 10 cycles, and the reduction was less than 15%. It can be seen from the static p-y curve of the pile foundation after cyclic loading that the larger the load amplitude, the greater the reduction in the bearing capacity of the pile foundation under cyclic loading. In addition, the reduction in the bearing capacity of the pile foundation under one-way loading is larger than that under two-way loading.