A mathematical model for determining the maximum impact stress on a downstream structure induced by dam-break flow in mountain rivers

Abstract

Breakage of a landslide dam can cause a great discharge during a relatively short time period, resulting in a large impact stress on downstream structures. A mathematical model is presented to analyze the impact stress on downstream structures introduced by a dam-break flooding event based on the energy balance theory, which takes into account both the dike shape and the channel conditions. The presented model is validated by laboratory tests; the error between theoretical values and experimental data is within 15 %, which suggests that the presented model is suitable for determining the impact stress introduced by a dam-break flooding event. Sensitivity analyses for the key model parameters are carried out, and simulated results show that the channel gradient and initial upstream water depth have a positive effect on the impact stress; however, the channel roughness and travel distance have a negative effect. Finally, the presented model is applied to estimate the impact stress on a structure from a dam-break that occurred in the Baisha River, southwest China. The effect of dike size on the impact stress is studied, and the maximum impact stress on a structure is 1,201 kPa when a full break occurs. This poses a great threat to the safety of the downstream region, and it is necessary to take effective measures to reduce the losses due to dam failure.