Asymmetric failure mechanism and control of entries in short-distance coal seam
Concentrated stress of the remaining coal pillars in the upper coal seam impacts gob-side en-tries driving process in the lower coal seam when both seams are close with each.This study aims at the problems of asymmetric deformation failure and support difficulties during the entry-driving process of 3#lower coal seam in Xiayukou Coal Mine.Multiple tools including mechanical analysis,numerical simu-lation and field test were combined with geological conditions,the asymmetric deformation mechanism during the entry-driving process of 23306 lower in-take airway was investigated,and reasonable support parameters and technical process were proposed,which improved the surrounding rock conditions.The results showed that the direction and value of the principal stress of the surrounding rock varied due to the existence of the remanent coal pillar in the upper coal seam and the neighboring goaf.The non-uni-form stress distribution produced a butterfly-shaped failure in the plastic zone of the surrounding rock.Due to the large variation of the horizontal stress and the large shear stress of the roof,the roof was ex-tremely cracked,and the whole area between the roof and the overlying goaf was plastic.The differential distribution of stress and plastic zone bilateral the roof was the main reason contributing to asymmetric deformation of the roadway.Numerical simulation indicated intense impacting of neighboring goaf in current seam on the stress state along X-Y,X-Z andZ-Z directions in coal pillars,and the different stress values bilateral the entry resulted an asymmetric deformation.According to the stress state of the sur-rounding rock,the geological conditions of the working face and the support cost,the support parameters were optimized,and the implementation in engineering field was satisfactory.
short-distance coal seamentryasymmetric deformationbutterfly-shaped failuresur-rounding rock control
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维普
