Study on the Characteristics of Water Jet Breaking Coal Rock in a Drilling Hole

Water jet technology is an effective measure by which to improve the efficiency of deep coalbed methane mining. Nevertheless, effect a water impinging on coal rock remains unclear. In this study, numerical simulation used analyze impingement drill test block, after experimental verification carried out. Next, basis that method feasible, influence factors in hole are analyzed. It concluded phase-field variables based fracture change can effectively characterize damage and destruction rock. The impact borehole has central failure zone two-side zone, ratio n degree When target distance 70 mm, closest 1, coal-rock best. wall roughness less than 10 blocking dominant, resulting negative correlation between size roughness. exceeds development cracks connection exceed effect, larger damage. Therefore, it be seen impacting positively related pressure. range 30 MPa pressure center both sides reaches about 1.1 m, thus signifying good breaking effect. significant jet.