| With the increase of coal mining depth,the support of soft rock roadways has become more and more difficult,and the phenomenon of surrounding rock fragmentation has become more and more serious,which seriously affects the safe and efficient production of coal mines.At the same time,numerous roadway renovations also incur huge costs.The support problem of soft rock roadway has become an urgent problem to be solved in the safe and efficient production of mines.This paper takes the roadway support of the 15 th coal left return airway in Beiru13 mining area of Yangmei No.2 Mine as the engineering background,and uses theoretical analysis,computer numerical calculation,model experiment and field test to study the deformation of the left return air roadway.According to the failure law,a reasonable bolt support design plan for the mining roadway was designed,and a support plan with high-strength pre-tightening bolt and cable support was determined.And through field measurement,it is verified that the deformation of the roadway after the use of high-strength pre-tightening bolt and cable support meets the requirements of roadway support and meets the needs of safe production in the mine.(1)The law of deformation and failure of the surrounding rock of the roadway is analyzed,and it is found that the surrounding rock of the roadway shows periodic failure,which is not conducive to the active support of the surrounding rock.The mechanism of high-strength pre-tightening bolt and cable support is systematically analyzed from the aspects of roadway supporting principle,bolt supporting mechanism and bolt pre-tightening force.With the support of high-strength pre-tightening bolts and cables,the integrity of the surrounding rock can be enhanced,the stress condition of the surrounding rock can be improved,and the self-supporting capacity of the surrounding rock can be improved.(2)The physical and mechanical properties of the roof and floor surrounding rocks of the left air return road and its hydrogeological conditions were systematically studied,and the separation situation of the roof and floor of the left air return road was grasped through drilling and peeping.Through underground sampling and laboratory rock Mechanical test,get the characteristics of the surrounding rock of the left return air tunnel.The analysis shows that the roof of No.15 coal is sandy mudstone,the strength is reduced,which is a weak rock formation,and the overall strength of each rock layer of the roof is reduced,and the surrounding rock needs to be reinforced;and the length of the bolt is preferably greater than 2m,and 2.4m long anchor is recommended.Rod.(3)The mechanical characteristics of the surrounding rock of the roadway under different support schemes are studied,and the analysis shows that: when the ordinary anchor-net-cable support is adopted,the stress concentration phenomenon of the surrounding rock of the roadway is obvious,and the pressure relief range of the roadway roof is relatively large.Conducive to the safe production of the mine.After the use of reinforced anchor mesh cable support,although the stress and strain have been improved to a certain extent,the stress and deformation conditions of the surrounding rock have not been completely improved,and the roadway still has a large deformation;the pre-tightening bolt anchor cable is adopted After the support,the stress concentration of the roadway is reduced,the pressure relief area of the roadway is reduced,the stress and strain of the roadway is improved greatly,and the roof of the roadway is effectively controlled,which meets the needs of safe production in the mine.(4)On-site monitoring of the surrounding rock deformation,roof separation,and bolt stress of the left return airway after the high-strength pre-tightening bolt and cable support was used for the left return air tunnel.The maximum deformations of the roof,floor,and two sides are respectively 23 mm,17mm,19mm;the force of the anchor rod is basically stable after 52m;the maximum total separation of the roof is7.5mm.The measured data shows that the high-strength pre-tightening anchor rod and cable support meets the support requirements.The paper has 43 pictures,3tables,and 92 references. |
