Resilient deformation characteristics of subgrade silty filler under intermittent train loading

Abstract

The intermittent loading method has been proved to be more realistic to simulate the long-term dynamic loading of trains on the subgrade, because the time interval of adjacent trains could be considered in this loading method. The plastic deformation characteristics under intermittent loading have been elaborated in previous studies, but the resilient deformation characteristics have not been reported. By carrying out a series of cyclic triaxial tests with intermittent loading, the resilient deformation characteristics of silty filler under intermittent loading were investigated. The test results indicate that the loading intermittence had a reduction effect on the resilient deformation, and this reduction effect was most significant for incremental collapse samples, followed by the plastic creep samples, and the plastic shakedown samples were the least. There was also a critical resilient strain for this silty filler under intermittent cyclic loading, beyond which the plastic strain developed rapidly to sample failure. A classification criterion for deformation behaviors based on the difference of resilient strain between the first and second loading stages Δεe,1-2, was proposed and then verified by other intermittent loading modes in which the intermittent duration and loading cycles per stage changed. Meanwhile, the limitations of this classification criterion were clarified, and a simpler method to identify the deformation behaviors of subgrade filler was presented based on the stable value of resilient strain under intermittent cyclic loading, which could satisfy the needs of railway engineers and workers to quickly evaluate the railway subgrade in service.