Overtopping-Induced Breach Mechanisms of the Asphalt Concrete Core Dam
Abstract
This study conducts flume model tests on the overtopping failure of asphalt concrete core dams (ACCDs), considering varying asphalt contents of core walls, environmental temperatures, dam heights to explore breach mechanisms for the first time. Test results show that the overtopping-induced breach process is divided into three stages: backward erosion of dam shell materials on the downstream slope until the first fracture of the core wall, multiple fractures of the asphalt concrete core until the occurrence of peak breach flow, and breach stabilization. The decrease of asphalt content or increase of the environmental temperature resulted in higher peak breach flow and earlier time to peak. These test results were employed to develop a predictive formula for the displacement of the core wall before its first fracture. The dam height significantly affects the peak breach flow but has little impact on the time to peak. A simplified numerical model is developed using the Burgers model, the principle of energy conversion, and fracture mechanics. This model accounts for the deformation and displacement of the asphalt concrete core wall after its exposure, the initial crack length, and the crack growth process. The calculated and test results show good agreement with less than ±15% relative error.