Laboratory full-scale model test of subgrade mud pumping for ballastless track of high-speed railway

This paper aims to clarify the mechanisms and driving factors of subgrade mud pumping for ballastless track in high-speed railway. A full-scale model test system in which the train dynamic loading and rainfall condition could be simulated was developed, allowing the recurrence of subgrade mud pumping. The relationship between the degree of mud pumping and the hydrodynamic pressure characteristics of subgrade was investigated, and the mechanisms and driving factors of mud pumping were also clarified. It was shown that the subgrade surface layer under the cracked concrete base was always saturated under the condition of rainwater infiltration, and it was prone to mud pumping given a long-term action of the dynamic loading of trains. A significant increase in excess pore water pressure to a certain extent mobilized the mud pumping. Accordingly, the prevention and treatment of mud pumping can be the prevention of rainwater infiltration or more efficient drainage.