Motion Analysis of Ground Failure Considering Rainfall and Ground Water Migration in Sandy Slopes

Failure of sandy slopes during heavy rainfall is often attributed to the rise of the groundwater table, which causes the slope to gradually transition from an unsaturated to a saturated state. Conventional methods for evaluating the stability of slopes under the influence of rainfall neglected the migration of groundwater and the dynamic motion of particles. In the current study, a model test is conducted to evaluate the trend of the groundwater table migration. In addition, a framework for partially saturated and unsaturated slopes is proposed for the dynamic process based on the analytical method. The results of the study show that based on the data analysis of the model tests, the upward trend of the groundwater table can be determined. Furthermore, the factor of safety (F_s) calculated from the analytical method shows that, F_s decreases sharply due to the upward migration of the groundwater table. The motion analysis provides the soil displacement and particle trajectory. This study provides an effective and practical method for evaluating the stability of unsaturated slopes under rainfall conditions, which can also be used for preliminary analysis in the early warning process.