Study on the law of coal and rock mass fracturing with different strength by pulse discharge stress wave

In order to reveal the effect of pulse discharge stress wave loading conditions (peak pressure) on the cracking effect and the change of vibration velocity of coal bodies at different ranks, the PFC^2D software is used to study the crack growth and vibration attenuation under different loading conditions. The results show that the number of cracks and the area of fracture increase first and then decrease with the increase of peak pressure. Under the peak pressure of 15 MPa, the number of cracks and fracture area of fat coal and coking coal reaches the maximum; when the number of cracks reaches the maximum in different coal ranks, the higher the coal rank is, the greater the peak pressure required is; under the same peak pressure, the lower the coal rank is, the more cracks are produced and the better the cracking effect is; it is verified that the peak pressure is related to the peak velocity of vibration. With the increase of the peak pressure, the velocity increases first and then decreases. Under the peak pressure of 15 MPa, the vibration attenuation amplitude of fat coal and coking coal is relatively gentle and the duration is relatively long. The attenuation of anthracite is the gentlest at the peak pressure of 35 MPa, so the vibration peak velocity is different under different peak pressures.