Coupled CFD-DEM Investigation of Erosion Accompanied by Clogging Mechanism under Different Hydraulic Gradients

Soil internal erosion refers to any process that the finer grains are eroded from the matrix of coarser grains due to seepage. A coupled computational fluid dynamics and discrete element method (CFD-DEM) analysis of internal erosion is conducted on bimodal soils. The coupled influences of hydraulic gradient i and fine content Fc on different domination process of internal erosion is investigated. It is found that the erosion degree does not always increase as i increases for underfilled soil (e.g. Fc = 10 % and Fc = 20 %), there is a hydraulic gradient threshold ith above which local particle clogging plays a dominant role, resulting in a smaller erosion degree instead, the ith is larger for larger Fc, when Fc is equal to 10, the ith is 2 or less, while ith is 4 for the soil with a fine content of 20 %. For transitional soil (e.g. Fc = 30 %), no obvious clogging domination under larger i is observed. The mechanism is revealed through both macro- and microquantity perspectives. It is found that local clogging is formed by particle bridge formation under larger i values. These findings are highly significant for further understanding the influence of i on the erosion process and establishing the erosion law.

Automated summary

Soil internal erosion refers to the erosion of finer grains from the matrix of coarser grains due to seepage. This study investigates the coupled influences of hydraulic gradient and fine content on different erosion processes using a computational fluid dynamics and discrete element method (CFD-DEM) analysis. The findings reveal the presence of a threshold hydraulic gradient above which local particle clogging dominates and leads to a smaller erosion degree. These findings provide valuable insights into the erosion process and can contribute to the establishment of erosion laws.