The Seismic Response Analysis Of Ground Soil With Variable Shear Modulus And Viscoelastic Ground Soil

The seismic response analysis of ground soil layer is one of important problems that should be considered in urban seismic regionalization, project ground seismic security appraisal and structure seismic design. It involves import seismic parameters of bedrock below soil horizon, seismic response analysis methods of soil horizon, soil dynamic parameters and others problems, and these problems mutually interact. Then, import earthquake motion, ground soil dynamic characteristics and other factors affect ground soil seismic response, so the geotechnical engineering and earthquake engineering circles attached great importance to the problem.In view of the complexity and uncertainty of free field seismic response analysis, for the sake of reasonably analyzing the effect of ground soil characteristics on ground seismic response, therefore, incident earthquake wave can be assumed to vertically upward incident harmonic horizontal polarization shear wave(SH wave), considering material damping of ground soil by linear hysteretic damping theory, proceed the soil layer seismic response analysis to three usual ground soil with variable shear modulus and viscouelastic half-space ground soil by utilizing one-dimensional shear beam theory, respectively obtain analytic solutions of different overlying elastic ground soils under bedrock motion import. As for single-layer ground soil, when shear modulus of ground soil is constant, or linearly vary with depth, or exponentially vary with depth, proceed contrastive analysis to three ground soil models. It is obvious that adopting ground soil model with shear modulus exponentially varing with depth more reflect heterogeneity characteristic of soil layer. Practical ground soil is mostly layered, so the local irregularities terrain effect on soil layer seismic response has been neglected. In the thesis, soil layer can be simplify to level layered system, seismic response analysis of single-layer ground soil can generalize to stratified soil, and soil layer seismic response calculation can be proceed by deterministic method or random vibration method. In addition, the solutions have been used to discuss the effect of different characteristics parameters on seismic response of ground soil. The analytic result indicated that the variation of exciting frequency, ground soil density, shear modulus, soil viscous damping ratio, impedance ratio, overlying soil thickness and other parameters have significant effects on structure seismic dynamic characteristics. It is obvious that adopting active aseismic design codes to conduct aseismic analysis to soil-structural system may engender major deviation, reasonably consider the effect of soil-structure dynamic interaction and material damping on ground seismic response characteristic. Seismic response characteristics of soil closely relate to soil parameter. Soil and structure should consider as the entirety, more reasonably embody the effect of layer configuration, soil property and soil- structure interaction on seismic response, obtain the analytical result that more accord with practical situation, so as to conduct optimum seismic design by select rational design parameters, and these results provide some references for further preceding the appraisal of earthquake site effect, earthquake damage analyses and structure seismic designs in the project.