Deformation characteristics of fine-grained soil under cyclic loading with intermittence

Abstract

Since there is an interval time between two trains traveling in the same direction on an automatically blocked line, the dynamic loading on the railway subgrade is composed of periodic vibration when the train passes and an intermittent stage after a train has passed. Take into account this characteristic, a series of continuous-stopping repeated load triaxial tests were conducted to study deformation characteristics such as plastic strain and elastic strain of fine-grained soil under intermittent loading. Compared to continuous loading, it is found that the intermittent stage has a significant effect on the deformation characteristics of subgrade. The excess pore water pressure accumulated during the loading stage dissipated during the intermittent stage. The development of plastic strain in subsequent loading stages slowed down significantly, and the axial strain of the sample rebounded in the intermittent stage, so cumulative plastic strain was reduced. The intermittent effect on reducing elastic strain was, however, limited. An increase in intermittent time can also improve the resistance of the sample to subsequent cyclic loading. An alternating continuous-stopping loading mode can better simulate intermittent loading of trains in actual train operation and produce more practical results, providing a theoretical basis and guidance for further understanding of deformation characteristics of railway subgrade.