Abstract
Due to a continual rainfall, a flowslide occurred in Yamashina area, Kanazawa City, Japan on November 8. 2002. The sliding mass was fully fluidized after slope failure and had deposited thickly in a bamboo area. The stratum around the landslide area was massive mudstone of Tertiary period. According to field investigation, the mudstone was classified into strongly weathered mudstone layer at top, densely cracked moderately weathered mudstone layer at middle and fresh mudstone layer at bottom . It is confirmed that the flowslide was initialized along the sliding surface between the densely cracked layer and the fresh layer, and the sliding mass moved in the strongly weathered mudstone layer. Based on the landslide motion simulation reproducing the Yamashina flowslide, the shear resistance at steady state in the strongly weathered mudstone area and the bamboo area were estimated as 10 kPa and 50 kPa respectively. It is concluded that the landslide with high mobility was caused by the low mobilization of shear resistance in the saturated strongly weathered mudstone with low permeability.
