Soil-Underground Structure Dynamic Interaction Considering Soil Nonlinearity

摘要

Soil-underground structure dynamic interaction is a complex scientific problem, which reveals the seismic responses of underground structures when an earthquake occurs. Most of the research currently being conducted ignores the effect of soil nonlinearity on underground structures owing to its complexity. However since soil is typically a nonlinear media, its nonlinearity has an important effect on the seismic responses of an underground structure. This paper proposes an approach to consider soil nonlinearity in a numerical analysis of soil-underground structure interaction dynamics. By using ANSYS finite element analysis software, the underground structure and the surrounding soil are modeled, and soil nonlinearity realized through the Davidenkov soil model by using the restarting method and ANSYS Parameter Design Language (APDL). The mechanics parameter, i.e. the shear modulus is forced to change along a cover obtained from experiments in each step of the numerical analysis. Therefore the nonlinearity of soil material can be considered. In addition, an artificial boundary is established to simulate a radiation damping effect for the model and the Combinl4 element is used as a viscoelastic boundary. The finite element analysis models of soil with and without an underground structure are respectively calculated under horizontal and vertical earthquake excitations. By comparing their results, The effect of underground structure on the free-field ground can be obtained. Finally the effect of different thicknesses of overlying soil on the underground structure seismic response is analyzed. Considering soil nonlinearity, this paper studies the seismic responses of soil-underground structure interaction under different seismic excitations and burial depths, derives a lot of conclusions from the theoretical analysis of the dynamic characteristics of soil-underground structure interaction and finally provides a theoretical basis for the engineering practice.