Simulation of Slope Failure Distributions Due to Heavy Rain on an Island Composed of Highly Weathered Granodiorite Based on the Simple Seepage Analysis
Takatsugu Ozaki*1,, Akihiko Wakai*1, Go Sato*2, Takashi Kimura*3, Takanari Yamasaki*4, Kazunori Hayashi*5, and Akino Watanabe*1
*1Graduate School of Science and Technology, Gunma University
1-5-1 Tenjincho, Kiryu, Gunma 376-8515, Japan
*2Graduate School of Environmental Informations, Teikyo Heisei University, Tokyo, Japan
*3Graduate School of Agriculture, Ehime University, Ehime, Japan
*4Japan Conservation Engineers & Co., Ltd., Tokyo, Japan
*5Okuyama Boring Co., Ltd., Miyagi, Japan
To fully and rapidly develop a real-time early warning judgment system for slope failure at the time of heavy rains including overseas, it is necessary to predict water movement in the soil at the time of rainfall. In addition, to apply the system to a place where insufficient geotechnical and geological data have been amassed, it is necessary to evaluate the risk of slope failure based on physical properties obtained from a simple soil test. Therefore, in this study, the authors set Gogoshima Island in Ehime Prefecture as a study site and evaluated the water movement over time in the soil during heavy rain using a simple prediction equation of rainfall seepage process. Soil properties were determined through simple in-situ and laboratory tests. As a result, it was found that the factor of safety for slope failure in the head and wall of a valley dissecting the hillside slope composed of granodiorite in which weathering has progressed can be planarly evaluated using the simple prediction equation.
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