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

Abstract

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.

Analysis of Influencing Factors of Subgrade Service Depth for Full Depth Asphalt Pavement

“…The insufficient bearing capacity of subgrade is one of the main reasons for the structural damage of pavement. Generally, the subgrade in the depth range where the ratio between the vertical stress of the wheel load σz and the vertical stress of the subgrade's own weight σb is greater than 1/10 ~ 1/5 is called the subgrade working area [1][2]. The influence range of driving load on subgrade is usually located in the subgrade service area, so it is necessary to ensure that the subgrade working area has sufficient strength, stiffness and stability.…”

“…In this paper, BISAR software based on elastic layered theory system is used to compare and analyze the vertical additional stress distribution along the depth direction of subgrade under the condition of full depth asphalt pavement and semi-rigid base pavement structure. The subgrade service depth of full depth asphalt pavement structure is determined according to the criterion σz / σb = 0.1 ~ 0.2 in literature [1][2]. In addition, the influence of different vehicle load and subgrade modulus on the subgrade working area of full depth asphalt pavement is analyzed.…”