抄録
Analysis of slope stability requires to assess a distribution of shear strength in the subsurface layer. In general, the depth of shallow landslide is range in 1 to 2 m from the surface, therefore it is important to make clear the property of shear strength at low confining stress. A series of direct shear test has been performed in order to examine the relationship between normal stress and shear strength at normal stress below 0.2 kgf/cm2.
The experimental evidence clearly shows that the failure envelope is curved for six types of soils, and the extrapolation by empirical Coulomb straight line is not suitable under this stress range. That is, the shear strength sharply decreases at normal stress below 0.1 kfg/cm2. Based on these results, we employ the nonlinear equation which the shear strength of soil is proportion to the powered normal stress in this paper.
