Experimental Study on Dynamic Response and Damage Evolution of Coal under Shocks by Multiple High-Pressure Air Blasting

To explore the dynamic response and damage evolution of coal under multiple high-pressure air blasting (HPAB), simulated specimens were used in HPAB experiments, variation laws stress field, vibration cumulative fracture failure process analyzed from a macro point view. A scanning electron microscope (SEM) mercury intrusion porosimetry (MIP) to observe pore distribution near blasthole specimen analyze law structure parameters microscopic The test results show that (1) wave generated by has great impact on zone. After HPAB, value at place 50 mm away increases 3.91 times compared with one shock strain peak velocity are reduced 17.86% 63.05%, respectively. With increase distance, internal damages middle far zones mainly driven air, peak, velocity, degree gradually decrease. (2) tests, attenuation index decreases first then increases, slowly few shocks rapidly. site coefficient ( k ) shows an overall decreasing trend, whereas id="M2"> ? tends increase. (3) HPABs have specimens. Compared unshocked specimen, injection volume increased 152.04% 135.05%, number connecting pores large diameter is significantly increased. can effectively improve form relatively developed network channel. study certain guiding for solving practical engineering problems low extraction efficiency permeability seams.