A Prediction Method for Slope Failure by Means of Monitoring of Water Content in Slope-Soil Layer
Masaharu Fujita*, Seitaro Ohshio**, and Daizo Tsutsumi*
*Disaster Prevention Research Institute, Kyoto University, Yokoohji, Fushimiku, Kyoto 612-8235, Japan
**West Japan Railway Company, 2-4-24 Shibata, Kitaku, Osaka 530-8341, Japan
Slope failure is generally predicted based on rainfall data. For example, a critical line for slope failure in an area is drawn on coordinates of hourly and cumulative precipitations, and we can predict that slope failure occur somewhere in the area when rainfall condition crosses the critical line into the occurrence region. As slope failure depends greatly on the water content condition in slope-soil layer before the rainfall event, the rainfall amount up to slope failure occurrence must be different. Also, such a method merely predicts the possibility of slope failure in the area at a time stage of the rainfall event. In this paper slope failure was simulated under different geographical and rainfall conditions, taking actual slopes as examples, and the simulation results indicate that water content in an individual slope-soil layer is an adequate index for predicting the collapse of the slope. The characteristics of sediment disaster such as the relationship between slope failure magnitude and rainfall condition is discussed and an idea for evacuation system for successively occurrence of slope failures based on the index is presented.
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