Deformation And Instability Law Of Roadway Surrounding Rock Under Coal Pillar In Goaf And Roadway Support Technology

In view of the difficulty in controlling the large deformation and instability of roadway surrounding rock affected by mining disturbance under the coal pillar in close coal seam mining,taking the 19112 auxiliary transportation roadway of China Coal Pingshuo Jinggong No.1 Mine as the research background,this paper studies the deformation characteristics of roadway surrounding rock under the coal pillar,the stress distribution law of upper coal pillar and lower floor of coal pillar by using the research methods of field experiment,laboratory experiment,theoretical analysis and numerical simulation The stress evolution law of roadway under coal pillar under the influence of mining is studied,the instability mechanism of roadway surrounding rock is summarized,and the control scheme of roadway surrounding rock is optimized.Firstly,the uniaxial tensile strength,compressive strength,shear strength,triaxial compressive strength and bulk compressive strength of coal and rock are measured.The results show that there is strain softening under the action of confining pressure,and the bulk shows linear hardening characteristics.The characteristics of large deformation of Roadway Under Goaf pillar affected by mining are summarized,and the problems of existing support are analyzed.Secondly,based on the theory of elasticity,the structural mechanics model of coal pillar and floor under coal pillar under different collapse degrees of overburden is established,and the stress calculation formulas of coal pillar and floor under coal pillar are deduced.The stress distribution of the coal pillar and the floor under the coal pillar under different collapse degrees of the overlying strata is simulated by using the strain softening Mohr-Coulomb Model and the Double-yield Model to simulate the goaf.It is proved that the collapse degree has an influence on the concentrated load of the coal pillar and floor.The stress distribution of different staggered distance between the lower coal seam roadway and the upper residual pillar edge is numerically simulated to explore the reasonable layout position of the lower coal seam roadway.Finally,based on the complex function and elastic mechanics theory,the structural mechanics model of rectangular roadway under coal pillar is established,and the stress calculation formula of rectangular roadway under support resistance is deduced.The three-dimensional numerical calculation model of roadway under the coal pillar affected by mining disturbance is established,and the stress evolution law,surrounding rock deformation characteristics and plastic zone development process of 19112 auxiliary transportation roadway under the joint action of coal pillar concentrated stress and mining disturbance are obtained,that is,the stress,surrounding rock deformation and plastic Zone Development of roadway are symmetrically distributed during driving along solid coal;The stress,deformation of surrounding rock and the development of plastic zone of the roadway are asymmetrically distributed during the excavation along the goaf,and its change process is affected by the mining lag effect of adjacent working faces.The change of roadway stress is basically stable after the influence range is about80m;During driving along the goaf,the stress,surrounding rock deformation and plastic zone development of the roadway are asymmetrically distributed.The mechanism of roadway instability is summarized.According to the asymmetric distribution characteristics of roadway surrounding rock,the roadway surrounding rock control technology of "bolt cable asymmetric support + grouting reinforcement + roof cutting pressure relief" is adopted,and the bolt(cable)support scheme,grouting reinforcement scheme and large-diameter drilling pressure relief scheme are designed.The field application verifies the control effect of roadway surrounding rock.The effect of roadway surrounding rock control scheme is good,which effectively alleviates the problem of large deformation of roadway surrounding rock..There are 58 figures,5 tables and 56 references in this paper.