Research on development and application of test equipment for measuring soil erosion characteristics

The soil erosion characteristics mainly include two indexes: critical shear stress for incipient motion of soil and soil erosion rate, which are controlling factors of breach flow and breach morphology evolution during embankment dam breaching. Traditional erosion experiments deduce flow shear stress by converting measured sectional flow velocity into friction velocity. This study has developed an innovative technique for directly measuring shear stress at the water-soil interface by using a bridge-type micro-strain shear stress sensor. Based on this method, a device for measuring soil erosion characteristics has been developed. The soil erosion testing device includes a hydrodynamic system, a soil erosion system, and a data acquisition system. The hydrodynamic system can provide water flow conditions ranging from 0 to 6 m/s. The soil erosion system utilizes strain sensors to directly capture dynamic changes in shear stress. By connecting a lifting device in parallel with an acoustic distance measurement device, a servo displacement control system is formed. This setup allows for adaptive adjustment of the specimen height and real-time monitoring of changes in erosion depth. Validation tests indicate that erosion rate of cohesive soils has a good linear correlation with water flow shear stress. Critical shear stress of cohesive soils significantly increases with higher compaction and clay content, while the influence of water content on critical shear stress is minimal. The paper also proposed a predictive model for critical shear stress and erosion coefficient of cohesive soil based on experimental data. Validation results show that the model can accurately reflect the relationship between the critical shear stress, erosion coefficient, and soil properties by optimizing model parameters and incorporating more soil-related features, which provide a scientific basis for selecting erosion parameters for dam materials in simulations of earth-soil dam failure.