EXPERIMENTAL ANALYSIS ON DYNAMIC CUMULATIVE DEFORMATION OF NANJING FINE SAND UNDER TRAIN-INDUCED VIBRATION LOADING

The earlier settlement of railway roadbed caused by train-induced vibration loading has great effects on the train driving safety if loose sand layers are included in the railway foundation. Accordingly, the GDS triaxial hollow cylindrical multi-function apparatus is used to model the real stress path of the train-induced vibration loading. The tested fine sand is distributed in Nanjing area, near to Yangtze rive. Its dynamic deformation properties are studied by taking into consideration of the drain condition and the confining pressure and the load amplitude. As results, the confining pressure has a greater effect on the vertical accumulated deformation of the test samples. The amplitude of vibration loading has a greater effect on the vertical accumulated deformation if the confining pressure is smaller. Also, the drain condition has a greater effect on the earlier settlement of roadbed than on the later settlement. At the same time, the new formulas and its parameters are developed and can be used to predict the vertical accumulated deformation of Nanjing fine sand with flake-shape structure. They are given based on the test results. These research conclusions can be used to predict the long-term settlement of railway roadbed with the newly deposited fine sand included in roadbed.