Study on Failure Mechanism and Control of Surrounding Rock of Secondary Mining Roadway in Thick and Hard Roof Coal Seam
Aiming at the serious problem of roadway deformation caused by the superposition of roof hanging and second-ary mining stress in fully mechanized mining face,taking the deformation failure and stability control of return airway in 31317 working face of Chahasu Coal Mine as the background,the numerical simulation method is used to study the failure characteris-tics of surrounding rock of thick and hard roof coal seam under secondary mining stress.The deformation and failure mechanism of surrounding rock in coal roadway under secondary mining of thick and hard roof is revealed,and the corresponding surround-ing rock control scheme is given according to the actual situation.The results show that the failure of roadway surrounding rock under the secondary mining of hard and thick roof reflects asymmetry.Different abutment pressure zones,the deformation of roadway on the side of goaf and the distribution of plastic zone have different characteristics.The deformation of the surrounding rock of the roadway on the side of the coal wall gradually decreases with the increase of the advance distance.When the work-ing face is located in different abutment pressure zones,the maximum roof subsidence is in the order of abutment pressure sta-ble zone>abutment pressure reducing zone>abutment pressure rising zone.According to this result,it is considered that the deformation and failure characteristics of roadway surrounding rock under secondary mining of hard and thick roof are mainly due to the difference of lateral abutment pressure of roof,and the unbalanced stress state of roadway roof and two sides of sur-rounding rock,which eventually leads to the subsidence of roadway roof in advance,thus affecting safe production.According to the above conclusions,the 'four-in-one' surrounding rock control scheme of advanced support,drilling pressure relief,bolt(ca-ble)support and grouting modification is put forward.
thick and hard roofsecondary miningsurrounding rock damagecollaboration support
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