Stability Analysis of Landslide Dam under Rainfall

Failure of a landslide dam might occur by river discharge or rainfall. A rise of the upstream water level of a landslide dam and rain infiltration into the dam body increase pore water pressure and the weight of the dam. In this study, transient seepage analysis of rainfall infiltration and dam stability analysis are performed. A two-phase flow simulation using the FLAC finite difference code is adopted to analyze unsaturated seepage flow in transient fluid-mechanical calculations. The safety factor of dam stability is evaluated using the shear strength reduction technique. The parameters discussed in this study include the rising speed of the water level, rain infiltration, and the hydraulic conductivity of soil. The results show that the time to slope failure of the dam is approximately 247 min. when only the effect of the rising upstream water level of the dam is considered. The failure time decreases to 189 min. when the rain infiltration and rising upstream water level of the dam are considered. The results also indicate that the hydraulic conductivity of the dam affects dam failure time.