Analysis On Wave Propagation In Two Dimensional Saturated Media

Wave propagation in saturated, porous media is an important subject in geotechnical and earthquake engineering. But because of the model's complexity, it is very difficult to solve the problem by use of analytical method, which is always limited in the very simple cases that are simplified in virtue of many kinds of assumptions. In order to solve the complicated problems, numerical method is preferred. So, some researches on numerical solution in analyzing the dynamic response of saturated, porous media are done in this paper. The main achievements could be summarized as follows:1) The dynamic response of the saturated, porous, elastic half-space is studied in this paper, and saturated soil is taken as elastic two-phase media. Numerical method, which is based on the soil mechanics model, is used for simulating the propagation of earthquake waves in two-dimensional saturated media. The four components of displacement of the soil skeleton and the pore fluid are taken as the unknown base quantities. And the explicit finite difference method, the combining method of the central difference method and Newmark s constant average acceleration method, and the transmitting boundary are used. By comparing the acceleration determined by the several methods of the displacements or velocities, a computing method of acceleration employed the one side difference of velocity is more practicality in this research. Corresponding to normal incidence of the body waves, P waves or SVwaves, and Rayleigh surface waves, two two-dimensional finite difference programs are compiled to compute the dynamic response of two-phase media.2) The dynamic responses of the saturated soil are analyzed respectively when the normal incident waves from bottom boundary are P-waves and SV-waves. The responses of the soil skeleton and the pore fluid are studied, while the influences of different permeability coefficient and the surmounting loads on the dynamic responses of two-phase media are expounded. Two boundary conditions of free surface of the saturated elastic half-space, permeable boundary condition and sealed boundary condition, are considered and the differences of the dynamic responses of the saturated elastic half-space are studied under the two boundary conditions.3) The dynamic responses are studied primarily when the normal incident waves from the lateral boundary are Rayleigh surface waves. The results of the dynamic response and the spatial waveforms are given. Through comparing the numerical solutions with the analytical solutions of one-phase media, the validity of the corresponding program is proved.4) Moreover, a simulating method avoiding the influence of initial inputting interrupt is put forward. The results prove it to be efficient.The results in this paper indicate that the two boundary conditions, permeable boundary condition and sealed boundary condition, of surface, permeability of the media, and surmounting loads of surface, all have influence on the dynamic response of two-phase media to a certain extent. And the research in this paper establishes the theoretical basis of the further study of inelastic saturated porous media.