Mechanism of loess planar erosion and numerical simulation based on CFD–DEM coupling model

Abstract

Planar erosion is an important mode of soil erosion, which occurs in the process of loess slope erosion, gully erosion, and cave erosion. It is of great significance to understand the characteristics and mechanism of planar erosion to reveal the mechanism of loess erosion and the prevention and treatment of soil and water loss. In this paper, a series of loess planar erosion tests have been carried out through self-developed large-scale loess scour instrument. The erosion process and stage characteristics of subsurface erosion under different conditions have been analyzed and summarized, and the internal mechanism of the loess planar erosion process in different erosion characteristic stages has been revealed. Then, based on the characteristics of loess microstructure, a discrete element fluid-solid coupling numerical model suitable for characterizing loess microstructure and anti-erosion property was established. The whole process of loess planar erosion is successfully inverted by numerical simulation. Loess has a special "nuclear + measuring" microstructure characteristics of clay attached to silt skeleton as cement particle surface connects skeleton particles, and the skeleton particles between the relay strength are directly related to the moisture content, the microstructure characteristics of powder of action between skeleton particles are very suitable for the connection with the discrete element keys to characterization. The numerical simulation results carried out based on the numerical model of inter particle linkage established in this paper are in good agreement with the main results of the physical simulation of planar erosion. The results all show that the loess planar erosion at the scale of large test blocks can be divided into three characteristic stages: uniform planar erosion stage, micro gully erosion stage, and collapse failure stage. This indicates that the fluid-solid coupling simulation method of CFD-DEM proposed in this paper has high simulation accuracy and has great application potential in the research and application of loess erosion. This provides a new and feasible idea for the study of loess slope erosion and hydraulic loss control on the Loess Plateau, which is worthy of further promotion.

Experimental and DEM-CFD Coupling Investigations on the Characteristics and Mechanism of Seepage Erosion for Cohesionless Soil

“…Pan et al [15] investigated the effect of head rise rates on erosion using an indoor device and found that different head rise rates led to different internal erosion damage patterns. Wen et al [16] used a self-developed large loess-scouring instrument to analyze and summarize the erosion process and stage characteristics of subsurface erosion under different conditions and revealed the intrinsic mechanisms of the plane erosion process of loess in the stages of different erosion characteristics. The behaviors of soils are highly stochastic under seepage.…”