Study on Adaptability of the Existing Subgrade to Train Speed-increase

Research purposes: Through continuous geophysical prospecting and in-situ test,physical and mechanical parameters of the subgrade are revealed to make a comprehensive evaluation of the subgrade and through train dynamic test,dynamic responses of the subgrade under different statuses are measured to make evaluation of adaptability of subgrade for the purpose of providing technical support for the train speed-increase on existing railway.Research conclusions:The real train dynamic test indicates that the average dynamic deformation and dynamic stress of the subgrade are close to that of passing current trains when passing freight trains at speed of 120 km/h,and the average dynamic stress of the subgrade is the 1/2 of passing current trains and the average dynamic deformation of the subgrade is the 1/3 of passing current trains when passing 200 km/h EMU.Based on a comprehensive analysis of the test results,this paper points out the main controlled elements of speed-increase subgrade,and presents the technical condition of speed-increase subgrade and the problems and vulnerabilities existed in speed-increase subgrade of existing railway.