Reliability-based design for earth-fill dams against heavy rains

To mitigate the disasters of decrepit earth-fill dams, improvement work is conducted. Since there is a recent demand for low-cost improvements, the development of a design method for optimum improvement work at a low cost is the final objective of this research. The reliability-based design approach is discussed as such a design method. Heavy rains are the most serious events for aged fill-dams, and sometimes overflows leading to breaching occur. From the estimated probability of overflow, the probability of submergence in the downstream is estimated for the reliability-based design. The remarkable point in this paper is that the probability of occurrences of heavy rains and the uncertainty of the soil properties are simultaneously considered for the design. Considering the disaster loss, the risk of submergence could be assessed.