Dynamic Modelling of Seismic Wave Propagation due to a Remote Seismic Source: A Case Study

Rockbursts are some of the most dangerous phenomena encountered in underground mines. They can be triggered by an abrupt ground disturbance from a remote seismic source. In this paper, the mechanism of remotely triggered rockbursts around a coal mine drift is analyzed using the synchro-squeezing transform (SST) method and dynamic modeling. Based on seismic monitoring data, the seismic waveform at the source is estimated through empirical scaling law and calibrated in the model. Then, with the SST seismic waveform decomposition codes, thePandSwaves are separated and filtered, and then applied in orthogonal oscillating directions at the source simulating their inherently diverse radiation mechanism. A three-dimensional numerical model was constructed with FLAC3D for a case study rockburst of a mine drift at Wudong Coal Mine. The static simulation results show that stress concentration occurs in the roof and rock pillar near the production level, and that the rock mass around the drift is already damaged due to the upper unloading effect and the bending deformation of the roof and pillar. Dynamic modeling confirmed that weak materials cause greater attenuation of particle vibration than hard materials. The rock mass around the drift experienced a significant strain energy release of 2.1 x 10(8) J and maximum displacements in the working face of 129 mm. ThePwave showed a larger contribution to the dynamic disturbance in the horizontal direction than in vertical direction, while theSwave has a predominant proportion in the vertical direction. As expected, particle vibration velocity and displacement on the north side of the drift are greater than those on the south side-under incidents waves propagating from the north side. Based on model results and peak particle velocity (PPV), it was deemed that the computed released energy is large enough to threaten the drift integrity, resulting in drift damage for up to 200 m from the working face. The predicted failure characteristics and potential damage range are consistent with field observations. The proposed approach of synchro-squeezing transform (SST) and dynamic modeling could prove useful in the assessment of damage in rockburst-prone areas-it could further help assess the need for and design of dynamic rock supports.