Cut slope damage of expressway caused by heavy rainfall in Tohoku district, Japan

Risk assessment of cut slopes on expressways attributed to heavy rainfall is required to maintain the expressway. Firstly, damage data for 25 years (1992-2017) are introduced from the viewpoints of the property of slopes. Secondary, this study has analyzed the rainfall patterns which is one of the causes of slope damage in order to establish the risk assessment method of expressway slopes. Hourly rainfall data was prepared by linear interpolation of rainfall data from three AMEDAS points adjoining to the objective place. Each rainfall event was determined when no rain condition had lasted for 6 or 12 hours. It was shown that 12 hours is better as criteria than 6 hours for determination of rain event and the spatial variation along the expressway are discussed.