| China is a mountainous country.Studying the influence of mountain topography on ground motions can help to estimate the seismic effect of mountain structures more accurately,which is beneficial to the earthquake prevention and disaster reduction of mountain buildings and is of great significance to the construction of mountain buildings.In this paper,the basic theoretical analysis and the verification of the finite element model of the viscoelastic artificial boundary in the semi-infinite domain wave problem are first confirmed,and the feasibility of the finite element analysis method is determined.Then the mountain terrain is simplified into multiple single platform models and multiple platform models.The model uses a lithological medium with a material density of 2500kg/m~3 and an elastic modulus of 6.25×10~9N/m~2.Through simulation,the acceleration response spectrum at each monitoring point of the platform model is obtained,and it is compared with the acceleration response spectrum without terrain effect to study the ground motion response law at each monitoring point.Finally,a reasonable value of the seismic amplification factor is given.The results show that:(1)in the simulation of seismic waves in the semi infinite region,the ABAQUS/Standard method and the ABAQUS/Explicit method have the same calculation accuracy,but the calculation efficiency of the ABAQUS/Explicit method is much higher than that of the ABAQUS/Standard method.(2)In the finite element analysis,the grid size is too large to restrain the effective propagation of high frequency seismic wave,and the grid size value is recommended not to exceed one tenth of the seismic wave length.(3)The top of the platform will obviously amplify the seismic waves.For a single terrain with a platform height of 10m to 800m,the horizontal ground motion amplification factor at the top of the platform terrain will increase first and then decrease with the increase of the platform height.The horizontal ground motion amplification factor reaches the maximum when the platform height is200m The value is 1.968;for 50m,100m and 200m platforms with three heights of 30°,45°and 60°slope angles and 50m top platform width,the horizontal ground motion amplification factor ranges from 1.396 to 3.252,and the greater the slope angle,the greater the ground motion amplification factor;for a single ground terrain with a platform width of 50m to 400m(100m platform height,45°slope angle),the larger the upper platform width,the smaller the horizontal ground motion amplification factor and the minimum horizontal ground motion amplification factor It is 1.338.(4)After analyzing the model of 200m platform height,50m platform width,45m slope angle,550m bottom width double platform,and 750m bottom width four platform model,it is found that the higher the relative height of the central platform,the closer the monitoring point is to the platform edge,the greater the terrain magnification effect(5)The analysis of the double platform and four platform models with a platform height of 200m found that the more platforms in the middle of the mountain,the larger the width of the bottom,the smaller the overall slope,and the smaller the terrain magnification effect at the top of the mountain. |
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