Study of dynamic characteristics of soil subgrade bed for ballastless track

Based on Suining-Chongqing high speed railway, the dynamic characteristics of ballastless track soil subgrade are analyzed through an indoor large-scale model test under dynamic loading. The result indicates that along the subgrade surface cross section, dynamic responses have the W-shaped distribution. But gradually become the basin-shaped distribution with the increase of depth. The largest dynamic response measured are under the concrete track position base, while the responses under the centre-line and the two ends of the concrete slab are smaller. The most intense dynamic responses are measured on the surface and graded gravel area; it reduces sharply with the increase of depth. Dynamic stress is slightly affected by loading frequency, while acceleration and dynamic deformation are fairly affected by it. In addition, a comprehensive field test has been conducted on the test course in Suining-Chongqing line by using CRH2-EMUs and freight train. The dynamic response of ballastless track subgrade under diffident speeds have been collected and the dynamic characteristics are analyzed. The results verify the suitability and adaptability of subgrade construction on Suining-Chongqing line.