Depression Seismic Conditions Of Oblique Incidence Topographic Site Effects

Local irregular topography has a great impact on earthquake ground motion.Topographic effect has been a hot focus in earthquake engineering.About effects of all kinds of topography on the surface ground motion have been a lot.Analytical method is not suitable for scarp topography for its characteristic.The studies of scarp topography are mainly under the vertical incident wave.About the study of scarp topography under the oblique incident wave was little.For scarp topography,using the method of the combination of finite element method and the artificial transmitting boundary,we discussed the influence extent and scope of the scarp terrain on scarp’s upside and downside ground motion under the P waves of oblique incidence with the help of software ANSYS.The main results as follows:(1)The influence degree and range of theβare strongly related to the incident waves.(2)β of the canyon’s side are generally larger than the bottom,and β of the side corner is larger than the top surface.(3)For fixed aspect ratio and SV wave incidence,the amplification factor increases with the increase of incident angle,and β of the x component is greater than the y component.Besides,β of left side corner is larger than the right.For P wave incidence,and β is also increases with the incident angle.The y component amplification factors at the two side corners of the canyon β decreases with the increase of θ.(4)For fixed θ,no matter of SV and P wave incidence,β of the canyon’s two sides increases with the increase of aspect ratio.For SV wave incidence,β of the x component at the left side corner is greater than the right ones,and β of the y component is less than the x.For P wave incidence,β of the x component at the left side corner is also greater than the right ones,and β of the y component is larger than the x component.