Mechanism of Sleeper–Ballast Dynamic Impact and Residual Settlements Accumulation in Zones with Unsupported Sleepers

Unsupported sleepers or void zones in ballasted tracks are one of the most recent and frequent track failures. The failures have property intensive development that, without timely maintenance measures, can cause appearance cost-expensive local instabilities such as subgrade damages. reason for lies mechanics sleeper ballast bed interaction. particularity interaction is a dynamic impact that occurs due to closure. Additionally, inhomogeneous pressure distribution between zone fully supported neighbour zones. present paper devoted studying mechanism sleeper–ballast zone. results experimental situ measurements rail deflections showed significant accelerations even lightweight slow vehicles. A simple three-beam numerical model rolling stock has shown similar measurements. Moreover, shows more than 3 times higher corresponding wheel point appears before enters point. analysis loadings specific behaviour combination with quasistatic part different zones, which characterised by high pre-stressed conditions. size influence demonstrates maximal appear at certain depth, after values decrease. loading indicates an increase 2 long voids almost full unloading short-length voids. However, used imitation cannot explain nature impact. clearly explained analytic solution using clamped beam. simplified analytical expression velocity it linearly related speed loading. comparison numerically simulated velocities good agreement existence depth An estimation long-term influences cases normal loading, pre-stress inside performed.