Influence From The Shape Of An Alluvial Valley Or A Canyon On Scattering Of Plane SH Waves

Site response problems are a kind of important problems in earthquake engineering. A lot of investigations of earthquake damage show that the existence of local sites affects the scattering and diffraction of seismic wave greatly. Accordingly, there are sensitive change of earthquake response of ground surface, underground structure and buildings in narrow spatial dimension. The local sites influence distribution of earthquake damage therefore. The estimation of the response in these sites under strong earthquake which may occur in the future is of great important, so the investigation of this kind of problem has important meaning on both theory research and practical project.Alluvial valley and canyon are two sorts of familiar ground in practical project. Based in this as engineering background, calculate the surface displacement amplitudes of arbitrary shape canyon and valley of cross-section and then make a mathematical analysis of these amplitudes.For the case of plane SH-waves incidence, the dispersing boundary method is adopted here. According to the boundary conditions, disperse the boundary of the canyon and alluvial valley of arbitrary shape. Numerical solutions are obtained by truncating the infinite equations and solved by least-square method.Thirty groups of random data are given, thirty arbitrary shape alluvial valley and canyon could be get by spline interpolation method. Calculate the surface displacement amplitude of these thirty arbitrary shape alluvial valley and canyon by the dispersing boundary method, mean value and standard deviation of surface displacement of the thirty canyon or valley are also given. The effects of frequency of the incident waves, the shape of the valley or canyon and the incident angle are analyzed. Some beneficial conclusions are given in the end of the thesis.