Saturated Soil-foundation-structure Dynamic Interaction Analysis

Analysis of soil-structure dynamic interaction subjected to seismic wave is a key problem in earthquake engineering.Due to the complexity of the problem,previous studies have considered the case of dry soil mostly.In practical engineering,soil is often filled with pore water.Pore water has a great influence on the seismic response of soil layer,and then influences the response of the foundation and the upper structure.Therefore,it is necessary to consider the saturated soil-foundation-structure dynamic interaction problem.In this study,the dynamic interaction is extended to the case of saturated soil,and the interaction of the saturated soil is discussed briefly.The main work is as follows:(1)Based on the Biot model,the response of saturated layered soil subjected to oblique incident seismic wave is obtained by using the Thomson-Haskell propagator matrix method.This method is validated by numerical examples.Two kinds of contraries to law of causality are found in numerical analysis.The range of parameters necessary for causality is obtained accordingly,which can be used as an upper bound in practice.(2)Using the spatio-temporal partition,explicit-implicit asynchronous algorithm,it is realized the analysis of saturated soil-foundation-structure system under earthquake through the FORTRAN program.Compared with the Belytschko explicit-implicit synchronization algorithm,it is proved that the proposed algorithm has high computational efficiency in the premise of ensuring accuracy.(3)The saturated soil-foundation-structure dynamic interaction problem based on the flexible foundation is realized.The rationality of the numerical simulation of the rigid foundation and the calculation instability of the flexible one are considered by numerical examples.(4)It is verified that the dynamic analysis of single-phase soil can be unified into the analysis of saturated soil.Thus,the soil-structure interaction analysis for the viscoelastic soil layered on saturated soil case is realized,which can approximate the ground water table in practice.The effects of ground water on the response of foundation and structure are examined through numerical examples of soil-structure interaction analysis for saturated soil,single-phase viscoelastic soil and the viscoelastic soil layered on saturated soil,and the results show that the ground water influences the structure and foundation responses greatly.(5)The Davidenkov model and the modified Masing rule is used to describe the nonlinear characteristics of the saturated soil skeleton.Numerical examples for three-dimensional analysis ofsaturated half space and saturated soil-foudation-frame structure system under earthquake are presented.The linear elastic and nonlinear saturated soils are considered respectively and the influence of nonlinearity on the response of saturated soil,foundation and structure is analyzed through comparison between the results of linear elastic case and nonlinear case.