Quantitative analysis of riverbank collapse mechanisms based on BSTEM

Abstract

ABSTRACT Riverbank collapse is a very common phenomenon in natural rivers that plays an important role in their evolution. In this study, we used the Bank Stability and Toe Erosion Model (BSTEM) to study quantitatively the effects of soil properties and bank inclination on its stability. For this, we investigated the stability of homogeneous banks under different bank inclination angles and binary structure banks composed of different materials. Our findings show differences between the cohesive and non-cohesive bank collapse modes, under the condition of ignoring the water table. We find the internal friction angle to be the dominant factor affecting non-cohesive banks, whereas cohesive banks are affected by the effective cohesion. The safety factor and water depth variations follow a quadratic polynomial law, more pronounced in non-cohesive banks. A higher inclination reduces the riverbank stability and safety factor. The latter is sensitive to bank slope changes for larger effective internal friction angles in non-cohesive banks. The material composition and thickness of the upper and lower layers of the riverbank with a binary structure affect the bank stability. The thickness and mechanical properties of the lower material play a key role in riparian stability.