Finite elements analyses of wave propagations due to a high-speed train across bridges

The finite element mesh of the unbounded wave problem often contains a large number of degrees of freedom. Moreover, the wave reflection along the mesh boundary cannot be avoided if only the traditional time-domain finite element method (FEM) is used. Thus, the main purpose of this study is to overcome those drawbacks and discuss how to use the three-dimensional FEM to simulate the soil vibration due to a moving high-speed train across bridges. A number of finite element analyses (FEA) including the isolation schemes of in-filled and open trenches were performed. The appropriate mesh dimension in the direction of the railroad is suggested and validated. Moreover, the 3-node wheel element for simulating the moving train and the least-squares method for finding foundation properties are proposed. Since the finite element mesh contains a large number of degrees of freedom, the conjugated gradient method with the SSOR preconditioning scheme is recommended. In conclusion, this study indicates that the difficulty of the FEA for unbounded problems can be overcome efficiently even by using a personal computer.