Mechanism and Control Technology of Roof Fragmentation in Excavation Tunnel
During the excavation of the 3110 return air channel in Qianhe Coal Mine,due to the influence of geological structure and adjacent goaf,the roof and side roadway of the goaf were severely fractured when the tunnel was excavated to 475 m.The traditional grouting reinforcement effect was relatively poor,resulting in poor formation effect,low excavation efficiency and high failure rate of permanent support.Therefore,the mechanism of tunnel surrounding rock fragmentation was analyzed,and based on the current support situation,a bidirectional pressure boosting reinforcement device was used for surrounding rock support in the fractured area of the tunnel.Through on-site practical application results,the phenomenon of tunnel surrounding rock fragmentation was significantly controlled after the optimization of support.The subsidence of the roof was controlled below 0.17 m,and the tunnel excavation speed was increased to 6.5 m/d,achieving significant application results.
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