Development of semi-physically based model to predict erosion rate of kaolinite clay under different moisture content

Abstract

Understanding the susceptibility of soils to concentrated flow erosion is imperative for predicting sustainability of various engineering structures and assessing environmental integrity. Currently, a widely used model is empirical in nature. In this study, we developed a semi-physically based model that predicts the rate of concentrated flow erosion of kaolinite clay based on tensile and erodibility characteristics. To develop this model, direct tensile tests and jet erosion tests (JETs) were performed on kaolinite clay with different percent moisture contents (MCs). The direct tensile test results showed that the energy required to break interparticle bonds across a fracture plane and tensile strength decreases with an increase in MC, whereas the JET results showed that soil resistance to erosion decreases with an increase in MC. Results also showed that an efficiency index of the JET apparatus, which represents the fraction of jet power used in actual erosion processes, diminishes with a decrease in MC. This semi-physically based model predicted the rate of erosion of kaolinite clay for a range of MC and applied hydraulic shear stress. In model development and verification, 98% and 90% of the data, respectively, were within a discrepancy ratio of 0.50 and 2.0.