水位急低下に伴う浸透挙動と安定性評価について

Abstract

Finite element saturated and unsaturated seepage flow analysis was done in this paper to study distribution of the residual pore water pressure generated in an embankment dam during a rapid draw-down and its influence on safety evaluation in the up-stream slope. Parametric studies were conducted on several model fills with different inclinations of slope by varying the decreasing rate of the reservoir level, to understand the mechanism of seepage flow during draw-down and variation with time of the residual pore water pressure accumulated in the embankment. Instability of slopes was then examined for two different patterns of failure, sliding failure due to a large pore water pressure and seepage failure due to a large hydraulic gradient. The results of slope stability analysis for circular slip surfaces revealed that the procedure of pore water pressure evaluation currently adopted in the design gives a safe side value of safety factor by around 10 to 20% as compared with the computed results.