2019 Volume 56 Issue 2 Pages 59-68
Shear displacements at different shear zones in deep-seated landslide, the Kojima landslide at Kochi, Japan was examined based on the measurement of vertical profiles of displacements in bore holes within the landslide mass and around the landslide area. Multiple shear zones were identified at a bore hole in active landslide area while only a shear zone was identified at the outside of the landslide. Shallower shear zones were identified within the landslide mass and deeper shear zone was identified at the bottom of landslide mass in active landslide area. Shear zones at different depths of a bore hole showed different response to rainfall. Shallower shear zone displaced depending more on the rainfall amount. While the displacement of deeper shear zone might depend more on the gravitational deformation. The increase of the displacement by heavy rainfall event is smaller at deeper shear zone than that at shallower shear zone. It suggests displacements under different deformation mechanism occurs in the deep-seated landslide.
