Study On Nonlinear Dynamic Soil-Underground Structure Interaction And Its Large-Size Shaking Table Test

Building of metro is main method to solve the congestion of city. The previous seismic damages of metro prove that restoration of it is very difficult as soon as it is damaged by earthquake. As far as urban earthquake disaster reduction planning are concerned, study on the earthquake resistant behavior of metro and its seismic design method are regarded more and more by people. For metro structure is embedded in soil, large deformation of soil is the major factor causing the severe damage of metro structure. Accordingly, study on the nonlinear dynamic characteristics of soil and the nonlinear dynamic soil-metro structure interaction are important.Firstly, the dynamic characteristics of recently deposited soils in area of Nanjing and its neighbor are studied and the nonlinear earthquake response of thick soft site is analyzed in this paper. Secondly, the nonlinear dynamic soil-metro structure interaction in thick soft site is analyzed by finite-element method to look-up its mechanics of damage and regularity of earthquake response. At last, the nonlinear dynamic soil-metro structure interaction is studied by shaking table tests. The dynamic responses of tunnel and subway station in liquable soil are surveyed respectively. These studies can be used to guide the seismic design of metro. The major studies are as follows:1. Based on the parabolic interpolation method, the chain formulas used to calculate the spectrum are deduced in detail. By comparing to those results calculated by precision method and analytic method, it proves that these results calculated by chain formulas are more precise than those results calculated by precision method. 2. The dynamic characteristics of recently deposited soils in area of Nanjing and its neighbor are studied. Referenced values of parameters used to fit the relationships of shear modulus ratio and damping ratio versus shear strain by new method are given.At the same time, the experiential formulas used to fit the relationship of maximal shear modulus versus confining pressure are also given in paper. Based on the Davidenkov stress-strain skeleton curves of soil, a new nonlinear viscous-elastic constitutive model of soil is constructed and its parameters are studied in detail. Based on the principles of geotechnical plastic mechanics, a viscous-plastic memorial nested yield surface model of soil is constructed.3. A new program used to calculate the nonlinear earthquake response of...