Progressive analysis of the progressive failure process of accumulated bank slope under dynamic water scour

Abstract

Objective In the southwest region of China, where canyons are deeply incised and water flows are turbulent, disasters frequently occur. The accumulated masses are widely distributed, and understanding the mechanisms and evolutionary processes of riverbank slopes composed of these masses under dynamic water scour, such as dam collapses and reservoir flood discharge, is of significant practical importance for hydropower, road construction, and urban development. Methods Building upon previous research, this study qualitatively analyzes the progressive deterioration of riverbank slopes under flood conditions. The development mechanisms of erosion grooves on both straight and concave riverbank slopes under dynamic water scour are theoretically derived. Furthermore, the multistage sliding process of the Ganhaizi landslide in Danba County, triggered by rising water levels, was simulated using Geo-studio software. Results A function describing the extent of erosion in straight riverbank slopes over time, considering factors such as water flow shear stress, slope shear strength, and initial shear stress was established. Both qualitative and quantitative analyses of the sliding process under dynamic water scour conditions show that erosion begins near the water surface and progresses inward, leading to traction landslides at the rear edge of the erosion groove. This is followed by erosion at the slope foot, resulting in continuously changes in slope morphology and multistage traction landslides. The Ganhaizi landslide experienced multiple traction stages due to a 15-meter rise in water levels and extended erosion time. Even currently stable bank slopes of accumulated masses remain vulnerable to large-scale sliding disasters under extreme hydraulic conditions. Conclusion This study offers a novel theoretical framework for analyzing riverbank collapse and provides guidance for preventing downstream disasters in water conservancy projects, such as reservoirs.

Keywords

• bank collapse
• failure mechanism
• stability analysis
• traction landslide
• dynamic water scour
• accumulated bank slope
• progressive failure