Basic Study on Use of Two-Phase Flow Method in Slope Stability Analysis

Abstract

In order to elucidate slope failure mechanism during rainfall, various analytical methods are being investigated. But there are few ones considering the influence of trapped air. If air is trapped in ground, smooth penetration of water is prevented and the ground may be collapsed by increasing pore air pressure. In this study, reproduction analysis of model experiments was performed by using two-phase flow analysis method considering influence of trapped air. As a result, it was shown that two-phase flow analysis may be more useful for evaluating slope stability during rainfall than single- phase flow analysis without considering the influence of trapped air. Since two-phase flow analysis is possible to evaluate influence of pore air on penetration of water and easily calculate relationship between saturation-suction and saturation-specific permeability. In addition, the reproducible analysis of slope failure site was performed by stress-flow analysis. As a result, the pore water pressure and the pore air pressure increased near the failure point during the torrential rainfall, in consequence, it causes the decrease of the effective stress. Hence, these were confirmed to be one of the factors that cause slope failure.