Numerical simulation study on the stability of coal pillar supported by end gang mining under the effect of blasting vibration

The stability of the supporting coal pillar is crucial to determining the safe and efficient popularization of highwall mining technology. In the meanwhile, the repeated and prolonged impact of mine blasting on the supporting coal pillar cannot be overlooked in highwall mining. Therefore, it is essential to propose a technically feasible parameter design scheme for supporting coal pillars under blasting vibration, taking into account specific circumstances. The attenuation law of blasting seismic waves is analyzed through in-situ vibration measurement in the south side of an open pit mine. A numerical simulation model is established to compare and analyze the vibration data obtained from numerical simulation with vibration measurement data, which verified the accuracy of the numerical simulation and determined the response law of blasting vibration. Based on instability and failure criteria for supporting coal pillars, a design scheme for supporting coal pillar parameters under different single charge amounts and blasting distances is proposed. The research findings show that peak velocity of blasting seismic wave is higher in horizontal radial and vertical blasts than in horizontal tangential blasts; there exists a nonlinear negative correlation between peak blast vibration velocity and distance from blast center; vertical attenuation velocity is faster than horizontal direction; main vibration frequency concentrates between 5-15 Hz, decreasing continuously with the increase of detonation center distance. Furthermore, based on the instability and failure criteria of supporting coal pillars and the limit caving distance of supporting coal pillar, the design scheme of supporting coal pillar width is optimized. The reasonable width of the supporting coal pillar is positively and nonlinearly correlated with single charge amount, negatively and nonlinearly correlated with blasting center distance.