Stability analysis of unsaturated soil slope during rainfall infiltration using coupled liquid-gas-solid three-phase model

作者：Dongmei Sun, Xiaomin Li, Ping Feng, Yongge Zang · 发表于：Water Science and Engineering · 年份：2016 · DOI：10.1016/j.wse.2016.06.008 · 被引用次数：50 · 研究领域：Soil and Unsaturated Flow、Landslides and related hazards、Dam Engineering and Safety

Generally, most soil slope failures are induced by rainfall infiltration, a process that involves interactions between the liquid phase, gas phase, and solid skeleton in an unsaturated soil slope. In this study, a loosely coupled liquid-gas-solid three-phase model, linking two numerical codes, TOUGH2/EOS3, which is used for water-air two-phase flow analysis, and FLAC3D, which is used for mechanical analysis, was established. The model was validated through a documented water drainage experiment over a sandy column and a comparison of the results with measured data and simulated results from other researchers. The proposed model was used to investigate the features of water-air two-phase flow and stress fields in an unsaturated soil slope during rainfall infiltration. The slope stability analysis was then performed based on the simulated water-air two-phase seepage and stress fields on a given slip surface. The results show that the safety factor for the given slip surface decreases first, then increases, and later decreases until the rainfall stops. Subsequently, a sudden rise occurs. After that, the safety factor decreases continually and reaches its lowest value, and then increases slowly to a steady value. The lowest value does not occur when the rainfall stops, indicating a delayed effect of the safety factor. The variations of the safety factor for the given slip surface are therefore caused by a combination of pore-air pressure, matric suction, normal stress, and net no...