Study on the Fine Particle Migration Characteristics of Silty Clay Under Cyclic Loading

The characteristics of railway subgrade mud pumping is that the subgrade soil forms mud and migrates upward along the pores of the track bed under the train load. The migration of fine particles will not only cause ballast fouling and reduce the elasticity of the ballast, but also lead to the reduction of the subgrade strength and the uneven settlement of the track, which seriously threatens driving safety. In this paper, the self-developed fine particle migration test device was used to conduct tests on saturated silty clay, and the effects of different cyclic loading amplitudes and initial dry densities of subgrade soil on the characteristics of fine particle migration were analyzed. Based on Computed Tomography (CT) scanning technology, the migration characteristics of fine particles in saturated silty clay under cyclic loading were studied from a mesoscopic perspective. The results show that with the increase in loading time, the mass of migrated fine particles increases nonlinearly, and the increase rate gradually reduces. The maximum mass of migrated fine particles increases with the increase of the cyclic loading amplitude, and decreases with the increase of the initial dry density of the subgrade soil. Finally, based on the test results, an evolution equation of fine particle migration mass under cyclic loading is established, and the accuracy and applicability of the evolution equation were verified by several groups of fine particle migration test data.