Influence of Joint Characteristics on Crack Propagation during the Double-Hole High-Energy Gas Impact Permeability Enhancement Process

In view of current research on the cracking mechanism of high-energy gas on coal, little attention has been paid to imitating the law of explosive blasting and cracks propagation, and the influence of joint on cracks propagation in the process of high-energy gas impact permeability enhancement has not been taken into account. In this paper, the effects of joint dip angles and joint lengths on cracks size propagation are studied by using a similar simulation test and RFPA2D-dynamic numerical simulation software. In the process of impact permeability enhancement of high-energy gas, the extension direction of the cracks is approximately parallel to the joint, and with the increase in the dip angle and length, the higher the number of cracks, the larger the extension range, and the closer it is to the permeability enhancement holes, the fracture network is formed. When the dip angle of the joint is 30°, the impact permeability enhancement effect results in an obvious zoning phenomenon. When the joint dip angle is 60° and 90°, there is a higher number of cracks and the cracks network is formed, and with the increase in the dip angle, the more the cracks develop and the better the impact permeability enhancement effect.