Investigating the mud pumping phenomena and dynamic characteristics in ballasted track subgrade under multi-stage/multi-frequency train load–wetting coupling

Abstract

In the process of expanding ballasted railway capacity, there is a significant increase in train axle load and speed, which leads to significant mud pumping disease under multi-stage/multi-frequency train load-wetting coupling, and its mechanism is still unclear. Mud pumping model tests from ballasted track subgrades under multi-stage/multi-frequency train load-wetting (MSC-W test/MFC-W test) coupling were conducted. The test results show that in the unsaturated state, the accumulated deformation of MSC-W test is more significant than that of MFC-W test, and the compactness of the subgrade filler is greater without significant particle migration. Under saturated or near saturated conditions, the MSC-W and MFC-W tests produces significant mud pumping by the driving force of dynamic pore water pressure. The amounts of mud pumping, fine particle layer displacement and void contaminant index (VCI) of the MFC-W test are significantly higher than those of the MSC-W test.