The sample soils were obtained from two landslides. The one is Uose where the slide occuered in a cut slope of decomposed shale and the other is Sannohji landslide area where the drainage wells were excavated for the drop of underground water level.
The triaxlal compression and the statically repeated simple shear tests were performed for the specimen which were prepared with the reconsolidation of slurry samples.
In Uose, the cohesion c' is 0.05kgf/<cm>^^^2 and the internal angle of friction φ' is 16.9゜from triaxial tests, but the stability analyses of the slide show that the cohesion of clay layer in shale is less than 0.015kgf/<cm>^^^2, because this value is obtained from the analysis ofφ'= 0.
In Sannohji landslide, the peak strength parameter c' and φ' are too great for the movement of the landslide. The residual strength paraeter c^'_r and φ'_r from repeated simple shear tests are applicable for this case.