Prediction model of the collapse of bank slope under the erosion effect of wind-induced wave in the Three Gorges Reservoir Area, China

During the storage period of the Three Gorges Reservoir, the bank erosion caused by wind-induced wave is getting more serious, especially for the crushed stone soil bank. The continuous wave scouring and erosion destabilize the bank slope and even induce the occurrence of landslides. Based on the energy conservation theory, the bank slope will reach a stable state after continuous wave erosion. Regarding this, this paper derives the prediction formula of the stable slope angle and erosion width when the wave erodes the crushed stone soil bank slope. Model tests on bank slopes with different dry densities and different crushed stone contents under the action of waves were conducted to observe the erosion process of wave-induced crushed stone soil bank slope and verify the proposed prediction formula. The results show that under the action of wave erosion, erosion ridge and collapse steep angle would form at the upper edge of the bank slope and the controlling factors of this process are the dry density of the crushed stone soil and the wave energy. When the content of crushed stone soil gradually increases, the ability of the bank slope to resist wave erosion weakens at first and then gradually strengthens. Comparing the erosion stable slope angle obtained from the model tests with the calculated results using the proposed prediction formula, a linear relationship could be observed, indicating that the proposed prediction formula is reliable for further analysis.