Study on the incipient motion of deposited particles caused by hydraulic erosion in mining-induced fracture: Optimizing the process parameters of HET

Abstract

Hydraulic erosion technology (HET) is a method of injecting a large amount of water into a blocked fracture to enhance its permeability. However, the incipient motion characteristics of the deposited particles in a fracture during hydraulic erosion are still unclear. This study conducted particle incipient motion experiments under the hydraulic conditions in a fracture, and investigated the particle incipient motion behavior and the variation in the characteristics of the threshold flow velocity with a change in the particle diameter. In addition, a new formula was developed to predict the threshold flow velocity of the deposited particle in the fracture, and the effects of fluid density, viscosity, and viscous sub-layer thickness on the threshold flow velocity were discussed. Furthermore, a method for optimizing the process parameters of HET was proposed. Results revealed that hydraulic erosion causes three particle motion states and four particle motion behavior in fractures. In addition, with an increase in the particle diameter, the threshold flow velocity first decreased and then increased. Further, increasing the fluid density and reducing the fluid viscosity were observed as two effective means for reducing the threshold flow velocity in fractures. Furthermore, an increasing fluid density was more sensitive to a reduction in the threshold velocity in fractures. These findings are expected to guide the optimization of the process parameters of HET.