Dynamic response of water saturated subgrade surface layer under high speed train using moving element method

Since the moving element method (MEM) is an elegant method for solving problems involving moving loads. This paper extends the moving element method to the dynamic response of the water-saturated subgrade surface layer under a high-speed train. The track model is described as the Euler beam to simulate the rail, concrete slab layer and elastic medium to simulate the concrete base layer. The water-saturated subgrade surface layer is characterized by Biot's dynamic poroelastic theory, and the other subgrade components are regarded as elastic medium. The governing equations are formulated in a coordinate system traveling at a constant velocity, and the associated finite element formulation in a moving frame of reference is derived. The proposed computational scheme is applied to investigate the dynamic characteristics of the water-saturated subgrade surface layer subjected to the moving train load. The effects of various key parameters including the train velocity, permeability, drainage boundary, elastic modulus and rail irregularity on hydro-mechanical response of the saturated subgrade surface layer are carefully analyzed.