2004年台風21号豪雨により香川県西讃地域で発生した斜面崩壊の地質・地形的特徴

概要

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Many slope failures and debris flows triggered by heavy rainfall associated with Typhoon 0421occurred in Seisan area, Kagawa Prefecture, Japan. Critical rainfall to trigger the slope failure is 65mm/h,150mm/3h, total precipitation 250mm, and soil water index 180. Many slope failures occurred at side-slopeand/or debris filled floor of 1-order valley in mountain slopes consisting of alternating beds of sandstone andmudstone (Izumi Group). Field evidence suggests that rainwater penetrated into permeable weathered sandstonelayer lying on poor permeable mudstone layer. Many slope failures occurred at weathered sandstone layerbecause of low strength and a rise in the groundwater level. The occurrences of slope failures were controlled byweathered profile of alternating beds of sandstone and mudstone.
徳島大学の論文