Influence Of Uneven Site On Seismic Response To Soil

The seismic response analysis of the soil layer in the construction site is an important part of the seismic safety assessment.Due to the influence of the project requirements,the form is simple,the parameters are easy to be determined,and the equivalent linearization method with small calculation amount is effective in the current site soil However,since this method does not have appropriate dynamic stress-strain relationship,it is not suitable for the site with uneven horizontal distribution of soil layers.According to the survey of seismic damage of all previous earthquakes,Earthquakes often exist in some of the damage and intensity are different from the surrounding venues for special venues,such as soft sites and special terrain and so on.Therefore,this paper conducts a related research on the seismic response of the site with unevenly distributed soil layers and some special terrain sites,which provides a foundation for the analysis of the seismic response of the soil layer from one dimension to two dimensions.The main research work is as follows:1.Finite element simulation of two-dimensional soil response to earthquakes.At present,the seismic response analysis method of soil layer adopted in the earthquake safety assessment work is the equivalent linearization method.This paper summarizes the basic principle of the equivalent linearization method,analyzes its advantages and disadvantages,briefly introduces its latest progress,On this basis,the method of two-dimensional seismic response analysis based on finite element simulation is introduced.The problems of model selection,constitutive relation,boundary condition processing and earthquake input are discussed.And the finite element method The viscoelastic artificial boundary is precisely applied,and the reliability of the procedure is verified through an example.2.The finite element analysis software was used to establish the soil model with unevenly distributed soil layers.The calculation results of the soil interface under different vertical angles of SV wave were discussed.The changes of the interface between the soil layers The seismic response of the ground surface provides some evidence for the selection of soil model in the seismic safety assessment.Compared with the case of horizontal stratification,the PGA magnification coefficient of the acceleration reaction time scale at the top of the model increases regularly or narrows linearly when the angle of soil decomposing surface changes.The softer the ground layer,the greater the acceleration response of the free surface,the more obvious the amplification effect of the site on the ground motion.At the same time,when the interface of medium is at an angle,the softer site is more sensitive to the change of angle.In this paper,the interface between medium at 15° and the interface at 20°Horizontal stratified 0 degree model has made a big difference.3.The finite element analysis model of the terrain effect of the local site under the action of seismic waves is established.The topographic effect caused by the vertical incidence of the SV wave in the valley-shaped site and the trapezoidal site is analyzed.The effects of the special terrain on the ground ground motion The numerical simulation results show that the local irregular terrain has magnifying effect on the movement of ground motion and whether the angle of slope foot of the valley-shaped site,the symmetry of the foot of the left and right sides and the aspect ratio are obvious for the valley and its surrounding area Impact.