Design Load of High-Speed Railway Subgrade Structure

The premise of carrying out structural design in high-speed railway subgrade was the explicit loading condition. Based on dynamic stress time curve by field measurement, the characters of load distribution on the subgrade came from analysis of axle load by ballasted track and ballastless track structure, investigation of the distribution mode of load on subgrade surface, and presentation of the formula of dynamic stress amplitude based on the mechanical equilibrium conditions. The paper came to the following conclusions: 1) Because of the good load diffusion effect of ballastless track, the two-axle loading of bogie work together to generate a loading and unloading cycle of the dynamic stress on subgrade surface which is different from ballast track. 2) The influence scope of the load transmitted through track to subgrade surface is a rectangle. It is simplified to be triangle distribution for ballasted track and trapezoidal distribution for ballastless track along longitudinal lines and to be uniformly distributed in lateral. 3) The computational formula of the dynamic stress on the subgrade surface and the design load amplitude were gained based on the load distribution mode.