Scattering Of Elastic Waves By Multi-Domain Coupling Complex Topography

The impact of complex topography on the ground motion is an important research topic in the fields of seismic engineering,geotechnical engineering,seismology and geophysics.It is worth noting that domestic and foreign studies have studied a single or a simple multiple topography.However,in fact,mountains,basins and rivers are all continuously distributed.The study on the influence of unit composite form of complex topography(such as mountains or basin-mountain coupling topography)on the ground motion is more realistic,which has theoretical significance and important engineering guiding value.In this paper,indirect boundary element method is used for studying the scattering of two-dimensional mountainous topography and three-dimensional basinmountain coupling topography.The main work is as follows.1.Scattering of seismic waves by mountainous topography: a new indirect boundary element method is proposed based on the periodic Green's function of inclined load in layered half-space.The scattering problem of elastic wave with periodic distribution of mountain is studied.The periodicity feature of the mountains is exploited to limit the discretization effort to a single mountain,which avoids errors induced by the truncation of the infinite boundary,and thus high accuracy is achieved and the demand of memory can be reduced greatly.2.The scattering of elastic waves by three dimensional basin-mountain coupling topography: the three-dimensional layered half-space basin-mountain coupling model is decomposed into basin closed domain,mountain closed domain and open layered half-space domain.In this paper,the three-dimensional scattering wave field in the open layered infinite space domain is constructed by moving slant load dynamic Green's function.At the same time,the three-dimensional scattered wave field generated by the uniform distributed load in the closed domain is modeled by the three-dimensional full space Green's function.Therefore,the method proposed in this paper can reduce the amount of computation as well as ensuring the accuracy of the result.In this paper,the correctness of the method is verified by comparison with the existing results.The dynamic interaction between complex topographies and the influence of complex topographies on the surrounding area are studied by numerical calculation and analysis.The results show that,for the mountainous topography,the decrease of the distance makes the dynamic interaction between the mountains more significant,and the peak value of the ground surface displacement amplitude increases more than 50%.For the basin-mountain coupling topography,there is a significant dynamic interaction between the sedimentary basin and surrounding mountains.With the increase of aspect ratio of the scattered mountains,the conversion of scattered waves between the basin and the mountain is more complicated.The peak value of the surface displacement even increased 3 times.