Dynamic settlement characteristics of piles based on stick-slip mechanism between piles and soils

The dynamic characteristics of the pile settlement under loads are studied based on the motion control equation for piles. Firstly, a pile-soil interaction model, considering the softening and recovery of resistance, is established by considering two contact states between piles and soils: sticking and slipping. Then, the established model and a modified tri-linear model are used to simulate the pile-side soil interaction and pile-tip soil interaction, respectively. A method for settlement of pile foundation considering the stick-slip mechanism between piles and soils is established in combination with the finite difference method. Finally, the stick-slip dynamic characteristics of the pile settlement and the mechanical characteristics of the pile are investigated based on the analysis method. The effects of the parameters of pile-soil interaction model on the dynamic characteristics of pile settlement are also analyzed. The results show that the dynamic characteristics of pile foundation with alternating sticking movement and rapid slipping movement are observed when the loads are close to the ultimate value of single-stage loading. The mechanical responses of piles are related to the loading path. Compared with those under single-stage loading, the shaft resistance of the pile can be better mobilized and the ultimate bearing capacity of the pile is higher under gradation loading. The proposed method can be used to simulate the settlement process of static loading tests on the piles.