Simulation Study of Coal Failure Law under High-Pressure Water Jetting

Abstract

High-pressure water jetting impinging on coal plays a relatively important role in improving pressure relief and permeability of the coal body, which can elevate the gas drainage effect and eliminate the outburst danger. But the slot formed by high-pressure water jetting impinging on the coal is affected by various factors in pressure relief and permeation of the surrounding coal. To explore how to improve the effect of pressure relief and permeability of the coal body in the process of high-pressure water jetting, the stress-strain and failure of the surrounding coal after the formation of slots were analyzed based on Fast Lagrangian Analysis of Continua 3D(FLAC3D) software, the influence and law exerted from each of the factors was screened out on pressure relief of the slot, and the mathematical model of the slot failure range was constructed. Results show that stress of slots impinged by high-pressure water jetting changes considerably in different directions. As vertical stress increases, the range of pressure relief and failure of the coal body gradually increase, and the pressure relief range enlarges exponentially with the increase of depth. The synergy pressure relief between slots can strengthen the pressure relief of the coal body. The findings obtained from this study can provide construction guidance and reference value for the onsite application of related hydraulic measures.

Keywords

• Failure law
• High-pressure water jetting
• Numerical simulation
• Pressure relief effect