| 17102(3)working face of Pansan Coal Mine is a typical deep inclined roof mining roadway with a buried depth of 800 m.Taking it as the engineering background,the analytical solution of the stress distribution of the surrounding rock of the inclined roof roadway is solved by using the conformal mapping function and the complex variable function method.Combined with the strength criterion,the stability index of the surrounding rock is defined,and the stability characteristics of the surrounding rock of the deep inclined roof mining roadway are obtained.Then,based on the plastic constitutive model of the bolt,two mechanical models are established to calculate the working resistance,axial force and shear stress of the bolt.The main conclusions are as follows:(1)The stability index of surrounding rock defined by combining the stress distribution and the strength criterion of surrounding rock can comprehensively reflect the influence characteristics of roadway stress conditions,geometric parameters of roadway section and strength parameters of surrounding rock on the local stability of roadway.Compared with the stress concentration factor,the stability index of surrounding rock is more reasonable.The mechanical model based on the elastic constitutive model can truly reflect the influence of the stress-strain relationship of the bolt on the mechanical properties of the bolt.Compared with the elastic and strain strengthening constitutive model,the plastic constitutive model is more reasonable.(2)In the inclined roof mining roadway of deep mine,the unstable area of high side is larger than that of the low side,and the stability of the high side is poor.The stability index of the surrounding rock of the two sides is smaller than that of the roof,and the two sides are more likely to be destroyed than the roof.The stability index of surrounding rock tends to 0 at the corner of the roadway,and the stability of the corner is the worst.The failure zone at the corner of the roadway develops mainly in the middle of the two sides of the inclined roof roadway and the middle of the roof,and the trend towards the deep part of the surrounding rock is relatively small.(3)When the bolt is in the elastic stage,increasing the pretension and anchorage length can effectively improve the working resistance of the bolt.After the bolt enters the yield stage and strain strengthening stage,increasing the pretension and anchorage length can not effectively improve the working resistance of the bolt.When the pretension and anchorage length are the same,the working resistance of ordinary anchor is less than that of high-strength anchor about 25 kN.(4)During roadway excavation and working face mining,the axial force of full-length anchoring bolt first increases and then decreases,and reaches the maximum at the neutral point of rock bolt.The derivative of the shear stress and the axial force of the bolt presents a positive proportional relationship,and the proportional coefficient is the reciprocal of the perimeter of the bolt.When the axial force of bolt exceeds the yield limit of bolt near the peak value of advance abutment pressure of coal mining face,the bolt enters the state of strain strengthening,and the axial force of bolt is basically unchanged along the direction of bolt body.(5)In the deep inclined roof mining roadway,compared with the end anchoring bolt support,the full-length anchoring bolt support can not only provide greater working resistance,but also provide shear stress along the direction of the bolt body for the shallow strata of the roadway,which is conducive to improving the stress state of the shallow strata of the roadway.At the same time,the working resistance of the full-length anchoring bolt at the roadway corner is much greater than that of the end anchoring bolt support,which greatly inhibits the development of the instability area of the roadway corner.Figure 101 Table 17 References 141... |
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