68 / 2023-05-22 10:32:17

Study on impact dynamic response characteristics and macro-micro damage evolution law of coal rock under electric pulse action

Coalbed Methane,Permeability,Electrical pulse,Shock wave,Breakdown voltage

Electric pulse technology is a new and efficient technology used to improve the permeability of coal seam. However, the impact dynamic response characteristics and macro-micro damage evolution law of coal rock under electric pulse action are not fully understood. Thus, a test system for improving permeability of coal rock cracked by electric pulse is developed, combined with shock wave test system and ultrasonic tester to carry out experimental research. The peak current, voltage waveform, shock wave propagation characteristics and damage change law of coal rock under electric pulse action are studied. The results show that the process of electric pulse breaking down coal rock takes several hundred microseconds, the higher the breakdown voltage is, the higher the peak current is. The peak value of shock wave at the same distance from the electrode center increases with the increase of breakdown voltage, showing a positive correlation trend. Under the same breakdown voltage condition, the peak pressure of shock wave decreases with the increase of distance from electrode center. When the electrical pulse acts on the coal rock, the fracture and fracture damage areas are formed along the breakdown center of the coal rock, and these damage areas show an increasing trend with the increase of the breakdown voltage. In addition, the ultrasonic wave velocity of coal rock decreases obviously and the damage variable value increases after the action of electric pulse.