| The subject, the effect of local complex ground conditions on the surface ground motion, has been one of the highly valued research topic in the earthquake engineering. Because of the limitation of calculation scale and artificial boundary conditions, the implicit method which need to solve equations often cannot complete analysis, while the time-domain explicit method combined with energy absorption boundary due to the explicit calculation characteristics of space-time decoupling, step by step recursive in time domain and reasonable matching local artificial boundary, often used in the analysis of this kind of problems. In this paper, based on the traditional time-domain explicit finite element method(FEM) and the viscous artificial boundary, the boundary of processing was implemented in ABAQUS to analyze the internal and external source problem in the classical field response, and compared with analytical solutions to research the calculation precision and solution reliability. The time-domain explicit finite element method uses linear interpolation in space discrete, so it has only one order accuracy, and in order to simulate and analyze problem better, this paper also used another numerical method which referenced to the field of earthquake engineering in recent years, the spectral element method(SEM). This method has the advantages of high calculation precision in space, fast convergence and easy realization of parallel computing, so it has become a important tool of seismic numerical simulation in the large scale model and complex geological structure calculation model. As well based on the explicit spectral element mentod and viscous boundary the paper simulated and analyzed the internal and external source problem, and compared them with the explicit finite element method or the reference solution to analyze the difference of the two numerical methods. Finally this paper used the explicit finite element method to study the influence of different analytic model of two-dimensional complex ground condition in actual engineering, and get a number of meaningful advice to actual engineering. The main work is embodied as follows:1. Firstly the paper introduced several important theoretical points of the explicit finite element method and the explicit spectral element method in inner domain, and analyze the high accuracy advantages and reasons of the explicit spectral element method, established the concrete expression of the viscous boundary on border, and achieved the viscous boundary and ground motion input of exogenous scattering problem on the computer.2. On the basis of the explicit finite element method and the explicit spectral element method loading viscous boundary the paper respectively established homogeneous elastic full and half space internal problem model, and comparatively analyzed the precision difference of the two explicit method and energy absorption of the viscous boundary.3. On the basis of the explicit finite element method and the explicit spectral element method loading viscous boundary the paper respectively set up circular canyon field model, semi-circular hill field model and circular canyon with covering layer field model, in time domain analyzed the simulation results of the two kinds of explicit numerical methods, in the frequency domain analyzed the effects of incident wave, incident frequency, incident angle and arc width on the surface ground motion of circular canyon field and semi-circular hill field.4. On the basis of the explicit finite element method the paper built two-dimensional complex field calculation model of different location in Wellington area, New Zealand, and compared the results of different calculation model of the conditions of topography, rock and overlay soil layers to study the establishment of reasonable model.5. The research of this paper was summarized, and on this basis I put forward the prospect of next research work in seismic wave problems of the two kinds of explicit numerical methods adopted in this article. |
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