浸透地下水流にもとづく斜面の崩壊

Abstract

Ground water flow may be generated in sloping soil layer laid on semi-pervious rock surfacewhen the infiltration of rain water exceeds in the downward leakage of water out of rock surface.This flow brings about the increase of shearing stress and decrease of compressional stress betweensoil particles through the drag force in the direction of flow and pressure gradient of pore water, respectively, and may result in slope failure. This paper is a theoretical report considered aboutthis type of failure. Taking account of the distribution of stress force, sloping layer is divided intotwo region, the one is upper layer (I) in wet condition due to the infiltration and the other is lowerone (II) influenced by ground water flow. According to the Mohr's theory of failure, the forma-tion of slip surface may be initiated in the layer (II) if it is occurred. At first, the necessary condi-tion of its formation is considered and, secondly, the drawing method of slip line is derived in activeand passive failure based on the conception of the limiting state of static equilibrium.