The Soil Dynamic Response Research Based On Finite-element And Boundary-element Hybrid Method

With the development of track traffic and the increase of train speed in China, people have began to give more and more concern to the influence of vibration induced by traffic load to around environment. In the context, it has very important value to research the calculated method of the dynamic response of soil under dynamic load.Understanding the mechanism of vibration generation and its propagation rule is the prerequisite to evaluate environmental vibration correctly and appropriately. The object of the paper researched is the influence of vibration around environment induced by city viaduct railway traffic system. Generally, the structure of city viaduct railway consists of track, rail pad, track pillow , box-beam and bridge pier. When train running on the track, there has interaction between whiles and track, and the track will bend because of the weight of wheel. The bend wave will propagate to box-beam and further to bridge pier. Then the vibration propagate to around soil through the bridge pier, which can cause the second vibration on buildings. Based on above analyses, the main ideas of this paper can be summarized as follows:1. The foundation and upper soil which variation much are discrete by using finite element method and other half-space soil is discrete by using boundary element method, because the FEM is better to analyzing the property of material and the geometry figure variation much while the BEM is better to analyzing the full-space or half-space problems. The coupling of the two domains is accomplished by imposing the conditions of continuity of displacements and tractions along the common boundary. The essential process of the hybrid finite-element and boundary-element method has been deduced in chapter two of the paper, and it is the basis of last.2. For the hybrid method presented in chapter two, developed a computer code applying Matlab computer language. By the step, we arrive to changing from theory to application.3. Calculating the propagation of foundation vibrate induced by impulse load to around soil make use of the code. Calculate the dynamic response of the point in surface with the different distance to the center of foundation, and compare the result to it get by finite element method(Ansys). Through the comparison, the hybrid methods is testified feasible and efficiently.In the end, the content of this paper has been summarized and some problem, which need further study, have been proposed.