Seismic Response Analysis Of Concaved Sedimentary Site In Suzhou City

Earthquake damage investigation and research at home and abroad have indicated that site conditions such as soil deposition characteristics and bedrock fluctuation degree have important influence on earthquake response.When the seismic wave propagates from the bedrock up to the surface,some frequency components may be significantly enlarged,and even produce the phenomenon of ?resonance scattering?,which will damage the structure built on it.Studying the characteristics of seismic response of complex site is to reveal the influence degree and influence rule of site conditions on earthquake response,and provide basic information for urban disaster prevention and mitigation planning,urban construction planning,land use planning and so on.Based on the study of the concaved sedimentary field in urban area of Suzhou City,different dynamic constitutive relations were chosen to establish two dimensional large-scale models,and the seismic response characteristics,mechanism and change rules of the concaved sedimentary site were discussed.The main research contents and results of this paper are as follows:1.Based on the detailed actual engineering data,the experience relation formula of shear wave velocity with soil depth in Suzhou city were abtained.Besides,the contour map of equivalent shear wave velocities were drawn and the spatial distribution laws of shear wave velocities were studied.2.The method of site seismic response analysis was expounded,and the theoretical basis of nonlinear seismic response analysis was summarized.3.Based on the finite element software Abaqus,large-scale refined two-dimensional(2D)refinement models for suzhou city were established,the viscoelastic artificial boundary and input ground motion automatically were realized.Considering the distribution characteristics of soil soil,the seismic response characteristics of two-dimensional horizontal uniform layer site and two-dimensional concave sedimentary site were compared and analyzed,and the influence of spatial distribution characteristics of the soil layer on the ground ground motion characteristics as well as the depth distribution of seismic dynamic along the soil layer was discussed.4.Considering the nonlinear characteristics of soil medium,the surface peak acceleration,the surface acceleration response spectrum and the seismic response characteristics of the ground motions are studied.It is revealed that the nonlinear constitutive model is closer to the real dynamic characteristics of soils,which may reflect the seismic response characteristics better.5.The suggested values of ground motion parameters in Suzhou urban area under different ground motion levels,the contour map of the surface peak acceleration,the characteristic period and the influence coefficient of the horizontal ground motion were given,which may provide reference for seismic safety evaluation in suzhou city.