Numerical Simulation of Effective Extraction Radius of Pre-Drainage Borehole Based on Coal Damage Model

Borehole pre-drainage is an important technical means to control a coal mine gas disaster. In order determine the optimal parameters of Dashucun mine, damage permeability evolution model was established based on deformation, considering adsorption and desorption Klinkenberg effect, fluid-structure coupling seam containing by combining deformation equation mass conservation equation. COMSOL software used simulate influence factors such as initial seam, negative pumping pressure, aperture time effective radius borehole. The results show that effect pressure extraction can be ignored. borehole aperture, great, which conforms power function relationship, coefficient correlation value high. are determined diameter 113 mm, 1 × 10?17 m2, 30 kPa 180 d. research provide theoretical reference for in mine.