Iterative Method for Predicting Uneven Settlement Caused by High-Speed Train Loads in Transition-Zone Subgrade

Uneven subgrade settlement associated with rail deflection occurs mainly in the bridge–embankment transition zones of high-speed railways. An iterative method of computation is proposed for studying such uneven settlement in these zones. A vehicle–track–subgrade model is used to investigate the vehicle–track interactions and the deviator stress field of the transition zone, and a soil cumulative plastic strain model is used to obtain the deterioration process of uneven settlement in the transition zone. Results indicate that uneven settlement caused by train loads in the transition zone tends to plateau at 40,000 repeated load applications. Subgrade settlement changes abruptly in the first measured 5 m, as well as from 25 to 30 m from the abutment; these two regions should be adequately strengthened and should receive more attention for track maintenance.