Based on the fast boundary element method and three-dimensional kinematic finite fault model,the ground motion of a complex site under the action of dip-slip fault is solved.Taking a three-dimensional near fault sedimentary basin as an example,the dynamic Green's function in the frequency domain is used to calculate the ground motion of the disbanded radiation field,and the phase change of the seismic wave in the frequency domain reflects the dynamic fracture process of the seism genic fault in the time domain,which breaks through the bottleneck that deterministic sources are challenging to simulate high-frequency seismic wave scattering.The seismic response in the time domain is obtained by designing the frequency domain and the adaptive inverse transform program of the fast boundary element method.The fast boundary element method simulation of ground motion based on a deterministic kinematic finite source model is real-ized in both the frequency domain and time domain.The amplification effect of near field sedimentary ba-sin ground motion under the dynamic fracture of dip-slip fault is analyzed quantitatively,and the coupling mechanism of near-fault effect and basin effect of an earthquake is revealed.The results show that there is an apparent coupling between the near-fault effect and basin focusing effect,which significantly affects the spatial distribution of ground motion in the basin area.The ground motion at the center of the basin is 3.97 times larger than the input ground motion near the fault.The permanent displacement decreases with the increase of fault distance.In the area of sedimentary basin,the duration of seismic motion is significantly prolonged,and the soft soil deposit amplifies the external input velocity pulse,resulting in large amplitude long-period velocity pulse;Sedimentary basins will dramatically increase the distribution range of near-fault strong earthquakes.This paper develops an efficient and accurate ground motion simulation method for near near-fault complex sites.The research conclusions are of great significance for seismic zoning near-fault sedimentary basins and seismic design of engineering structures.
fast boundary element methoddip-slip faultsedimentary basinnear-fault effectsite effect
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