Dynamic behavior of precast epoxy asphalt track bed for transition zone in high-speed railway: A numerical approach

Abstract

Elastic cured track bed is gradually used in high-speed railway construction for its high deformation tolerance and stress reduction capacity. Polyurethane and asphalt mixture are the most popular materials used in construction of such track. The usage of polyurethane is restricted by its high cost and constant stiffness at all sections, which causes unwanted deterioration in transition zone. Four kinds of dry-mixed rubberize epoxy asphalt mixture (DREAM) with different stiffness were designed and fabricated into prefabricated asphalt block used as the underlayment of the transition zone of a high-speed railway in this study, aiming to achieve smooth change of stiffness in the transition zone through dynamic response evaluation. To emphasize the feasibility of DREAMs and the special arrangement method proposed in this study, a 3-dimensional transition zone finite element model was established using the finite element software ABAQUS. Dynamic responses related to structure and material working conditions were specially calculated and compared with polyurethane track. The simulation results indicates that the DREAM has better performance under the load of 350 km/h high-speed train compared with polyurethane track. In addition, arrangement method of the four kinds of asphalt block composed of DREAMs was proved efficient in achieving smooth change of stiffness. Compared with polyurethane track, DREAM track has a better stress reduction capacity and plays an important role in protecting the substructure. Besides, structural deterioration of the asphalt mixture is much lower than the recommended value through the results of vertical deflection on the bottom of asphalt block. Finally, the maximum elastic strain and maximum vertical stress on the bottom of asphalt block were specially calculated, and the results indicate that they all meet the recommended values applied to the high-speed railway.