TXT-tool 3.081-1.4: Initiation Mechanism of Rapid and Long Run-Out Landslide and Simulation of Hiroshima Landslide Disasters Using the Integrated Simulation Model (LS-RAPID)

Abstract

On August 20, 2014 many landslides and debris flows occurred in Hiroshima city during the heavy rainfall. Ring shear apparatus (ICL-1) was used to simulate the failure of soils, the formation of sliding surfaces and the steady-state motion of Hiroshima landslide disasters. Samples were taken from source area in Midorii and Yagi district. The ring shear tests on Midorii and Yagi samples were carried out under the normal stress of 50 and 100 kPa that assumed the landslide depth from 4 to 8 m. The triggering factor such as pore-water pressure was calculated by using the Slope-Infiltration-Distributed Equilibrium (SLIDE) model that developed by Liao et al. (Landslides 7:317–324, 2010, Environ Earth Sci 55:1697–1705, 2012). The rainfall record monitored at the Miiri JMA station for each 10 min from 8:30 PM on August 19, 2014 was used to calculated pore-water pressure and landslide occurred when pore-water pressure reached 15.2 kPa. All test results were input to an integrated simulation model (LS-RAPID) as dynamic parameter of landslide. The combination of landslide ring shear simulator and integrated landslide simulation model provides a new tool for landslide assessment. The hazard area and time of occurrence in Hiroshima disaster were estimated by LS-RAPID. The estimated hazard area is similar with landslide moving area reported by Geospatial Information Authority of Japan (GSI). This research will contribute to understanding the mechanism of landslide and debris flow during heavy rainfall as a basic knowledge for disaster prevention.