Dynamic Stresses in Embankment and Ground Caused by HST with the Considering of Track Irregularity

Scientific design of a railway track formation requires an understanding of the dynamic stresses in embankment and ground. To study the dynamic stress, the time-history of stress, and the stress development with train speed are essential, especially in embankment. This study investigates the dynamic stresses both in embankment and ground, by means of a high-efficient 2.5D track-embankment-foundation numerical model. Based on China’s first high speed railway, a 2.5D ballast track model is established. In order to study the effect of track irregularity, the track irregularity PSD of U.S. railways is adopted to the ballast track model. The in situ test results of ballast railways collected from predecessor’s research are summarized and normalized to compare with the 2.5D numerical results under different grades of track irregularity. Based on the comparison, a preliminary division of the irregularity of track running state can be made. Track irregularity of a new built railway was less than six grade track irregularity PSD of U.S. railways. But for some diseased lines or longtime operation lines, track irregularity were in an extremely serious condition, even larger than first grade track irregularity PSD of U.S. railways. The numerical results also shows that the amplification of dynamic stresses caused by track irregularity is limited at low speed stage (≤100 km/h), and at high speed stage, the dynamic stresses show a multiple increase. The track irregularity also cause deeper transmission and wider influence area in embankment and ground. Larger dynamic stress will caused a larger deformation in embankment and track structure which aggravate track irregularity in turn.