Abstract
The stability of slopes in landslide areas are usually analyized by using shearing strength obtained from laboratory test.
However, in the great majority of such analyses, the results are different with actual soil behaivor. At one time the soil mass has moved, it is very difficult to predict whether progressive failure occure or not with the time passed. To make clear these phenomena, the author carried in situ shear test and decided upper yielding trength and failure strength. It is also discussed on the basis of large scale creep test under loading for a long periods in situ, whether the upper yielding strength is boundary of creep failure or not.
