Nonlinear dynamic behavior of laterally loaded composite caisson-piles foundation under scour conditions

Abstract

A simplified method for predicting the nonlinear dynamic response of composite caisson-piles foundation (CCPF) under scour conditions is proposed. The Hardin-Drnevich model is employed to represent the nonlinear soil reactions. Stress history is also considered to study the scour effect on the dynamic impedance of foundation. Then, harmonic vibration tests considering scour are conducted on a CCPF. It can be observed that the predicted trends of the CCPFs response agree with the experimental data, which verifies the reliability of the method. Then, a case study is investigated to evaluate the effects of stress history, scour depth and soil nonlinearity on the dynamic response of the foundation. The results show that soil nonlinearity has a close relationship with the lateral dynamic displacement of foundation, and it will result in a slight reduction in the resonant dimensionless frequency of the CCPFs. Additionally, with increasing scour depth, a remarkable decrease in the dynamic impedances is produced when soil nonlinearity is considered. Compared with soil nonlinearity, stress history is found to have greater influence on the displacement of the CCPFs, especially in the low frequency range. Finally, a discussion is conducted on the relationships between the resonant frequency of the CCPFs and the scour depth.