Research on the Countermeasure of Railway Subgrade on Existing Railways

The problem exposed on railway subgrade is found more and more serious with the development of speed raise scope and the increase of train speed. The researcher in the railway system has slighted the technical condition of speed raise subgrade. The subgrade improvement has become a key item in the project of the Jing Qin passenger line, which will provide a 200 km·h -1 service. The author analyzes the technical conditions in terms of high speed railway research results in such areas as the bed of subgrade, the transition of bridge and subgrade, and the settlement of subgrade. The investigation and test on main line subgrade are overviewed, the distribution of dynamic stress, the relationship between stress and speed, and the relationship between stress and track irregularities are analyzed also. The main technical condition of speed raising subgrade on existing railway is suggested. Some static test, non destructive test and treatment are introduced in the article. The test uses the light dynamic cone and the geologic radar guided by the experience of the Jing Qin line and the test results proves to be effective. Several general effective improvement methods are also introduced.