HR: 16:45h
AN: S54A-06    [Abstracts]
TI: Mitigation of Earthquake-Induced Catastrophic Landslide Hazard on Gentle Slopes by Surface Loading
AU: * Trandafir, A C
EM: atrandafir@yahoo.com
AF: Slope Conservation Section, Geohazards Division, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Sidle, R C
EM: sidle@slope.dpri.kyoto-u.ac.jp
AF: Slope Conservation Section, Geohazards Division, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Kamai, T
EM: kamai@slope.dpri.kyoto-u.ac.jp
AF: Slope Conservation Section, Geohazards Division, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AB: Catastrophic landslides have occurred repeatedly on gentle slopes during past earthquakes in Japan, sometimes causing great loss of life and significant environmental damage. Reconnaissance reports on the October 23, 2004, Chuetsu earthquake in Niigata Prefecture, Japan, also include collapse of gentle slopes associated with damage to roads and railways which lost foundation support. Additionally, investigations of the spatial distribution and features of landslides triggered by the Chuetsu earthquake revealed that 23% of the landslides mapped within a 2.9 km radius around the major earthquake epicenter occurred on slopes with gradients between 10 and 20 degrees. Past experience demonstrated that such earthquake-induced catastrophic landslides occurred along shear surfaces in saturated cohesionless materials, and the main factor controlling the high mobility of the slide mass after failure was the gradual loss in shear strength with progressive shear displacement. Given the high rainfall prior the earthquake, it is likely that the same failure mechanism characterizes the catastrophic landslides triggered on gentle slopes during the October 23, 2004, Chuetsu event in Niigata Prefecture. Thus, we introduce a procedure based on application of an additional confining stress to the surface to increase the stability of gentle slopes in saturated cohesionless soils subject to catastrophic failure during earthquakes. This surface pressure is achieved by concrete plates tied back with prestressed steel anchors which penetrate through the soil well below the potential sliding surface. Results of a dynamic analysis of undrained seismic performance conducted for a gentle infinite slope that experienced different levels of increase in effective confining stress due to a uniform load applied normal to the surface, illustrate the effectiveness of this measure in mitigating the earthquake-induced catastrophic landslide hazards.
DE: 5470 Surface materials and properties
DE: 7212 Earthquake ground motions and engineering
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2005 Joint Assembly