10:15 〜 10:30
[HDS08-06] Fault constraints on a deep-seated landslide in fragmented metamorphic rocks<br _mstmutation="1" />
キーワード：High-density electrical resistivity tomography, Geological Strength Index, Baige landslide, Deformation and failure mechanism, Deep-seated gravitational slope deformation
Two landslides occurred on the western side of the Jinsha (98°41'52.05" E, 31°4'30.86 N), China in October and November 2018, respectively, which is known as the Baige landslides. The landslide events with a total volume of 3050×104 m3 disturbed the slope composed of gneiss, schist and slate. This study employs a multidisciplinary approach, including the field investigations, unmanned aerial vehicle (UAV) photogrammetry, high-density resistivity measurements (ERT), and microscopic rock analysis. The results showed that the average Geological Strength Index (GSI) within the landslide area is 19, constituting only 64% of the average GSI outside and 86% of the average GSI along the landslide boundary. Widespread shear, tensile fractures and flexural folds related to rock creep are observed in the landslide source area. The linear concave landforms parallel to the summit slope confirm deep-seated gravitational deformation. Two inclined faults were observed to constraint the landslide boundaries. These faults not only induce fragmentation and creep of the rock mass but also act as permeable layers, intensifying the infiltration capacity of groundwater at the boundary. The geological and hydrogeological structures were thought to cause the landslide unstable. This study highlights the specific slope landforms associated with gravitational deformation as valuable geomorphic indicators for identifying landslides on fractured slopes constrained by faults.