2021 Volume 16 Issue 1 Pages 49-61
As for the landslide that occurred during the excavation construction of the road in Mine-shi, Yamaguchi Prefecture, based on the results of the countermeasure method examined by the committee of experts, it was proposed to excavate the gradient of the cut slope to about “i=1:2.0” and to discharge the unnecessary earth. Due to the shape of the cut slope, it remained stable for a long time after the road was completed. However, the landslide occurred again 40 years after opening. Since the landslide had occurred in the past and from the sings of past behavior, sliding and resting had repeatedly occurred in this block of landslide, and it was determined that the sliding surface strength is in a residual state. Therefore, it was necessary to adequately consider the residual strength when examining the stability of the slope. This paper reports a case where the landslide surface was determined for two sliding surfaces adjacent to the cut slope based on the soil survey and dynamic observation results from existing documents, and the residual strength constant obtained by the ring shear test and the strength constant obtained by the inverse analysis method was roughly the same.
