Study On Surrounding Rock Stability Of Deep Roadway In Suburban Coal Mine

At present,with the continuous increase of mining depth,roadways and working faces will be located in the environment of high-strength in-situ rock stress field and strong mining.Structural stress and poor engineering characteristics of rock mass increase the difficulty and technical requirements of mining operations.The suburban coal mine of Zhenglong Coal Industry adopts multi-level development of vertical shaft.In recent years,the mining level of mine has gradually transited from shallow to deep,and the depth of main mining seam is over 800 m.With the gradual increase of mining depth,the damage and destruction of surrounding rock become more and more serious.The rock pressure shows strong catastrophic phenomena such as roof fall,floor heave,coal and rock slice,support failure,coal and gas outburst,etc.It is difficult for existing support to maintain the normal use of roadway.In this paper,the distribution law of stress field and the dynamic response characteristics of roadway rock pressure with the mining of working face are obtained by field measurement and numerical simulation.The definition of damage variable of deep roadway is given,and the influence mechanism of mining activity on roadway surrounding rock damage is studied and analyzed.The loosening circle of surrounding rock,roadway damage and roadway damage are obtained.The relationship between roadway deformation and the supporting technology of deep horizontal roadway and gob-side entry retaining technology of roof cutting and pressure relief in suburban coal mine are studied,and the field application effect is good.The main contents of this paper are as follows:1.Distribution law of in-situ rock stress field in deep part of suburban coal mine and dynamic response characteristics of mine pressure in RoadwayThe stress relief method is used to measure the original rock stress of the second level deep roadway in the suburban coal mine,and the field test results are compared with those of other surrounding areas.The results show that the suburban coal mine after deep mining belongs to high strength in-situ rock stress environment,which has great influence on the stability of surrounding rock of deep roadway in suburban coal mine.The distribution characteristics of the original rock stress field in 21304 working face are inverted by theoretical calculation and numerical simulation.The theoretical calculation results and numerical simulation results are in good agreement with the field monitoring results.Based on the engineering background of two-level west-wing track roadway and 21305 track roadway,the mine pressure of open-up roadway and quasi-mining roadway were monitored in situ.The monitoring results show that the dynamic response of surrounding rock deformation,roof separation and bolt load of open-up roadway and quasi-mining roadway is more intense with the mining of working face.The original supporting method can not maintain the normal use of roadway,and the rock pressure appearance of quasi-mining roadway is more intense than that of open-up roadway.2.The influence mechanism of mining activity on surrounding rock damage of roadwayThrough the method of borehole photography in coal seam,the scope of loosening zone of surrounding rock during roadway excavation and mining is detected and analyzed.The results show that roadway excavation and mining cause different degrees of damage to surrounding rock,and the surrounding rock is in an unstable state.The definition of damage variable of roadway surrounding rock is given,and the theoretical calculation formulas of fracture zone and plastic zone are deduced.On this basis,the variation of damage variable of roadway surrounding rock under uniform and non-uniform confining pressure is analyzed.The influence mechanism of surrounding rock damage on roadway rock pressure is studied,and the relationship between the scope of surrounding rock loosening zone and damage variable and roadway deformation is analyzed.With the increase of the scope of the loosening zone,the deformation of roadway and the amount of roof separation are increasing.Therefore,the displacement of surrounding rock surface can be predicted according to the scope of the loosening zone,which provides a reference for the stability study of surrounding rock under the conditions of roadway driving and working face mining.With the increase of damage variable,the deformation of roadway and the amount of roof separation increase gradually,which lays a theoretical foundation for the new support scheme.3.Surrounding rock support mode and effect evaluation of deep roadwayAccording to the problems existing in the displacement and stress distribution of the two-level west-wing track roadway in the field monitoring,three new supporting schemes are put forward.These three schemes make the roof and floor approaching and convergence of the two sides of the open-up roadway decrease in varying degrees,and the field application effect of the second scheme is good.According to the problems existing in the displacement and stress distribution of 21305 track roadway in site monitoring,five new supporting schemes are put forward.These five schemes all reduce the roof and floor approximation and convergence of both sides of the mining roadway.The field application effect of scheme 4 is good.By comparing and analyzing the deformation and roof separation of the exploited roadway and the exploited Roadway after adopting the new support scheme,it is found that the deformation and roof separation of the exploited Roadway after adopting the new support scheme are still larger than those of the exploited roadway because of the influence of mining disturbance and other factors.4.Application of No-pillar Mining Technology for Roof Cutting and Pressure Relief along Gob-side Retaining Roadway in Deep RoadwayThe 110 working method of roof-cutting and pillar-free self-forming roadway changes the roadway from passive "branch" to active "cut" and "branch".By using rock pressure and surrounding rock movement,the stress transfer of roof is cut off,the force transfer structure between roof strata is changed,and the newly formed roadway is in the pressure relief zone of mine,which can effectively improve the problem of stress concentration in surrounding rock of roadway and relieve the stress response of Plateau rock.The threat of force environment to the stability of surrounding rock reduces the deformation of roadway and reduces the difficulty of surrounding rock control.This paper improves the surrounding rock support mode of the second level deep roadway in suburban coal mine by implementing 110 mining method of roof cutting and pressure relief along goaf retaining.By comparing the field monitoring results of 110 mining method with those of the new supporting scheme,it is found that 110 mining method has good application effect in deep roadway,which can significantly reduce the deformation of roadway and improve the stability of surrounding rock.