Propagation and attenuation characteristics of rockburst-induced shock waves in coal-rock medium

Abstract

Avoiding resonance effect of roadway is very important to prevent the rockburst hazard triggered by shock wave interference in coal mines. Propagation and attenuation characteristics of shock waves in coal-rock medium at the working face at Zhuji Coal Mine were investigated by using dynamic analysis in a three-dimensional finite difference code, FLAC3D. We revealed the attenuation properties and resonant effect of shock waves at different frequencies. It was found from the numerical analysis that the intensity of shock wave attenuates exponentially with the increasing propagation distance, while the horizontal attenuation coefficients of stress are very small. The vertical attenuation coefficient of shock waves is much larger than the horizontal attenuation coefficient. Due to existing roadway, the attenuation coefficient of amplitude in x-direction is larger compared with that in y-direction, while the attenuation coefficients of vibration velocity in x-direction and y-direction are almost equal to each other. Along with the propagation of shock waves, the high-frequency components gradually attenuate, and the frequency moves to low-frequency band. When resonance occurs in 35 Hz, the intensity values of shock waves reach the maximum value. Therefore, the resonance phenomenon can stimulate the maximum vibration response of underground structures. The low plastic deformation around the roadway indicates that the surrounding rock mass may induce rockburst more easily.