Vertical dynamic impedance of pile groups embedded in soils considering the groundwater level

The groundwater level divides the soils into unsaturated zone and saturated zone, imposing an indispensable effect on the soil–pile interaction behavior. In this work, the groundwater level is introduced into soil–pile group interaction models for advancing the dynamic impedance research of pile groups. The motion equation of pile groups is modeled by the finite element method. The vibration solution of soils considering the groundwater level is solved via the precise integration method, which is utilized as the kernel function to construct the boundary integral equation. The coupled finite element method (FEM) and boundary element method (BEM) establishes the unsaturated soil–pile group interaction equation, which is further solved based on the soil–pile compatibility condition. After confirming the reliability of the above theory, parametric analyses are provided to discuss the effect of a series of key parameters on the impedance function of pile groups.