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Coal Engineering ›› 2024, Vol. 56 ›› Issue (9): 105-111.doi: 10.11799/ce202409017

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Numerical simulation on roof and floor blasting rock burst prevention for nearly vertical coal seams#br#

  

  • Received:2024-03-13 Revised:2024-06-27 Online:2023-09-20 Published:2025-01-08

Abstract:

Due to the compressive and prying actions of the roof and floor, preventing rock bursts in near vertical coal seams presents considerable challenges. This study focuses on the Wudong Coal Mine's southern mining area, investigating the blasting pressure relief methods for the roof and floor rock bodies in near-vertical coal seams. Using case studies, numerical simulations, and onsite validations, this research analyzed the effectiveness of deep-hole blasting measures during rock burst occurrences in near-vertical coal seams. Although deep-hole blasting reduces the dynamic loads caused by the compressive and prying actions of the roof and floor, it is less effective in weakening the nearby rock mass at the working face and reducing static loads. To address these shortcomings, this study introduces a combined deep and shallow hole blasting method that mitigates the dynamic loads from prying actions, effectively weakens the rock mass at the working face, and reduces the concentration of static loads. The techniques include alternating deep and shallow hole blasting and simultaneous deep and shallow hole blasting. Compared to single deep-hole blasting, both methods further reduce the peak horizontal stress in the surrounding rock of the roadway. The simultaneous deep and shallow hole blasting shows better rock burst prevention effects than alternating blasting but at a higher engineering cost. In the southern mining area of Wudong Coal Mine, alternating deep and shallow hole blasting has been applied. Microseismic monitoring results indicate that, compared to deep-hole blasting alone, the implementation of combined deep and shallow-hole blasting significantly reduced the occurrence of high-energy events (greater than 104J) from 9.3% to 0.2% and shifted the microseismic energy from "low-frequency high-energy" to "high-frequency low-energy," effectively mitigating the risk of rock bursts. These findings provide significant support for preventing rock bursts in near vertical coal seams.

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