Two and Three Dimensional Slope Stability Analysis of Landslide Dam Failure due to Sliding

Abstract

不飽和多孔質媒体内の流れは，水と空気の2相流れの問題となる。本研究では間隙内空気の流れの効果を考慮するために，多相流理論に基づき水と空気の2相流モデルの導入を行った。これまで天然ダムの斜面の安定解析では，突然の決壊を予測するために，間隙水圧と含水率を解く従来の水相流モデル，水と空気の2相流モデルによって解析されており，そのモデル内はJanbuの簡易的な方法だけでなく，平衡状態に基づいた拡張Spencer法などが用いられている。本研究では，拡張Spencer法を用いて2相流れを解析しており，実験結果とも比較的良く一致した結果が得られている。

Water flow in unsaturated porous media is water- air two-phase flow problem. To incorporate the effect of pore air flow in the soil seepage analysis a water-air two-phase flow model, based on the multi-phase flow theory is used. Slope stability analysis of land slide dam has been carried out using pore water pressure and moisture content calculated by only a conventional water-phase flow model as well as the water-air two-phase flow model so as to predict the failure of dam due to sudden sliding. Janbu's simplified method as well as extended Spencer method based on limiting equilibrium considerations is used in slope stability analysis. Overall simulation results obtained by considering two-phase seepage flow combined with extended Spencer method of slope stability analysis are comparatively in good agreement with the experimentally observed results.