Development of combined tank model and saturated-unsaturated flow simulations and its application to the slope stability problem

摘要

Slope failure/collapse due to heavy rain occurs frequently and causes serious damages and losses of infrastructures. For the slope stability analysis, porewater pressure and its distribution along the potential sliding planes as well as their time evolution will be the most sensitive and important factors. To evaluate the porewater pressure distribution properly, a new technique combining the tank model and saturated-unsaturated flow simulations was proposed in this paper. Using this technique, the field condition can be represented more realistic by adjusting time-dependent hydraulic head boundary conditions as well as the infiltration of the rain water. The tank model was applied at both sides of modeling area to predict groundwater level variations due to rainfall intensity pulse. The groundwater level was derived from the components affecting water entering and leaving the system. The numerical flow simulations were carried out to estimate groundwater level within the modeling area controlled by physical characteristics of the system such as unsaturated soil properties. This proposed method was also implemented into the real field slope stability problem in Japan. Verification was carried out by comparing estimated groundwater level with a set of observed data. The flow simulation results show a good agreement with the observed ones.