急勾配斜面の崩壊発生機構に関する実験的研究 Experimental Study on a Mechanism of the Steep Slope Failure
急勾配斜面の不飽和状態の崩壊発生機構を解明するために, 砂質土斜面の崩壊実験と不飽和試料の三軸圧縮試験を行った。その結果斜面のせん断変形過程は, 三軸圧縮試験におけるせん断ひずみと飽和度の関係より基本的には説明しうることが判明した。
In order to examine the mechanism of the collapse of steep unsaturated slope, 2 types of experiments were carried out. One is the series of the laboratory model experiments of sandy steep slope failure caused by artificial rainfall. Another is the series of triaxial compression tests of the sandy soil under different saturation ratios.<br>As the results of these experiments, deformation characteristics of unsaturated soil mentioned below have been made clear.<br>(1) The basic relationship between shear strain of the unsaturated soil and saturation ratio is hyperbolic. If the saturation ratio becomes larger, the shear strain becomes larger.<br>(2) If the normal stress becomes larger, the hyperbolic curve of the laboratory tests between the shear strain and the saturation ratio moves to the higher saturation ratio region. But, on the contrary, the relationship curve of the triaxial compression tests moves to the lower saturation ratio region if the confining stress becomes larger.<br>(3) In the laboratory tests, the relationship between shear strain and saturation ratio moves to lower saturation ratio region if the surface slope gradient becomes larger. This result of laboratory tests coincides with the fact that shear strain proceeds in the lower saturation ratio region if the stress ratio becomes larger.
地すべり 32(4), 1-8, 1996-03-15