| In this paper,based on the engineering background of the return air chute of the 8507 working face of Longbo coal industry of Datong Coal Mine Group,the influencing factors of the stability of the surrounding rock and the reasonable width of the coal pillar are studied by the method of field investigation,theoretical analysis,numerical simulation and industrial test,and the appropriate surrounding rock control technology and parameters are selected by combining the research conclusion and the specific engineering geological conditions.By using the method of field investigation and theoretical analysis,the causes of the deformation of the surrounding rock in the excavated section of the return air chute of 8507 working face are studied.The results show that the main reasons for the deformation of the surrounding rock are the different lithology of surrounding rock,the influence of lateral supporting pressure,the disturbance of driving and the unreasonable stoping and supporting parameters of the adjacent working face;the peak value of lateral supporting pressure is about 10 ～ 12 m away from the surface of the roadway;the stability of the large and small structures of the roadway along the goaf is good for the maintenance of the roadway The width of the limit equilibrium zone is 12.84 m.Based on the L16(45)orthogonal table design orthogonal test,the FLAC3 D numerical simulation software is used to study the influencing factors and degree of the stability of the surrounding rock of the narrow coal pillar driving along the goaf.The results show that the width of the coal pillar has the highest significant influence on the stability of the surrounding rock of the roadway;Based on the actual engineering geological conditions of the return air chute in the 8507 working face of Longbo coal industry,the deformation,stress and plastic zone distribution characteristics and change rules of the surrounding rock of the roadway under different pillar widths are studied.The results show that with the increase of the width of coal pillar,the deformation of surrounding rock of roadway decreases gradually and the degree of reduction decreases gradually.Under different width of coal pillar,the asymmetric deformation characteristics of "deformation of coal pillar side > roof subsidence > deformation of solid coal side > floor heave" are presented;With the increase of the width of coal pillar,the internal stress of coal pillar increases gradually,and the stress concentration degree increases gradually;With the increase of the width of the coal pillar,the plastic zone of the surrounding rock of the roadway presents a dynamic reduction process of "left shoulder angle of the roadway → roof of the roadway → right shoulder angle of the roadway";the reasonable width of the coal pillar is 8m.In view of the specific engineering geological conditions of the return air chute in 8507 working face,the corresponding surrounding rock control strategy is determined,four support schemes are proposed,and the FLAC3 D numerical simulation software is used for comparative analysis.Finally,the asymmetric support scheme of "roof and two sides of Anchor Mesh Cable +side channel steel beam + W steel belt + narrow coal pillar side grouting reinforcement" is determined,which can control the surrounding rock deformation of the roadway and the side of the coal pillar at the same time Strengthen support;The field industrial test results show that during the roadway driving and 8507 working face mining,the approach of roof and floor is 119.3mm and305 mm respectively,and the approach of two sides is 167.4mm and 420 mm respectively;the asymmetric support scheme of "roof and two sides of anchor net cable + side channel steel beam +W steel belt + narrow coal pillar grouting reinforcement" can effectively control the deformation and damage of the surrounding rock of the roadway and alleviate the asymmetric support of the roadway The characteristics of deformation and failure ensure the stability of the roadway during the service period. |
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