Study On Cracking Failure Characteristics And Control Technology Of Surrounding Rock In Deep Coal Roadway

Deep coal roadway is often affected by excavation and mining.Primary cracks,structural planes and new cracks in surrounding rock of roadway occur,expand,penetrate and even dislocate rapidly,which eventually leads to cracking,destruction and even instability of roadway surrounding rock.Therefore,the characteristics,mechanism,support principle and control technology of surrounding rock cracking in deep coal roadway need to be solved urgently.Based on the engineering geological conditions of 21304 mining roadway in Chengjiao Coal Mine,the characteristics of surrounding rock cracking failure in deep coal roadway are analyzed by means of field test,analogy simulation,theoretical analysis and field test.The mechanism of surrounding rock cracking failure in deep coal roadway and the supporting principle are studied.The control technology of "strong wall and roof protection" for surrounding rock in deep coal roadway is put forward,and the "strong side" of 21304 mining roadway in Chengjiao Coal Mine is formulated.The "roof protection" control scheme provides some basic data support for surrounding rock cracking failure characteristics,cracking failure mechanism,support principle and control technology of deep coal roadway under horizontal stress,and provides certain theoretical basis for supporting design of deep coal roadway.This paper mainly studies as follows:1)By means of on-site testing method,the characteristics of surrounding rock fracturing and failure during excavation and mining disturbance of 21304 mining roadway in Chengjiao Coal Mine are measured and analyzed,that is,the development of side cracks during deep coal roadway excavation under horizontal stress,the rapid development of side and shoulder cracks during mining disturbance,and even roof instability.2)The physical and mechanical parameters of surrounding rock of deep coal roadway were measured by using the similar simulation test method of cracking failure characteristics of surrounding rock of deep coal roadway.By means of acoustic emission,dynamic strain acquisition instrument and high-speed video camera,the displacement law of rock stratum and stress distribution of surrounding rock of roadway were analyzed,the cracking failure sketch map of surrounding rock of deep coal roadway was depicted,and the linkage cracking of roof of deep coal roadway was studied.Failure effect and fracture characteristics of surrounding rock.3)The characteristics of surrounding rock fracturing and failure of deep coal roadway are analyzed.The shallow surrounding rock of deep roadway wall is obviously strained by mining.The deep surrounding rock gradually changes from compressive strain to tensile strain.With the increase of load,the range of deep tensile strain becomes larger,the cracks of roadway surrounding rock develop,the strength of roadway surrounding rock weakens,and the bearing capacity of roadway wall decreases.As the load continues to increase,the tensile strain range in the deep part of the roof continues to increase,the cracks in the roof develop rapidly,and the bearing capacity of the roof continues to decline,which eventually leads to the increase of the roof subsidence and even the roof instability and failure.4)The surrounding rock control principle of "strong roof protection" in deep coal roadways is put forward.The strength and stiffness of support in deep coal roadways are strengthened,the degree of cracking of two sides is controlled,and the roof anchor rope support is carried out step by step.Combining the suspension theory with the composite arch theory,the roof subsidence is controlled and the overall stability of roadways is improved.Surrounding rock control technology of deep coal roadway includes roof control technology of deep coal roadway,side control technology of deep coal roadway and shoulder angle control technology of deep coal roadway.5)Field tests were carried out.Based on the characteristics of surrounding rock fracturing failure in deep coal roadway,combined with the mechanism of surrounding rock fracturing failure,supporting principle and control technology in deep coal roadway,the support scheme of "strong support and roof protection" was formulated.Through field tests in 21304 mining roadway in suburban mine,the roadway deformation was effectively controlled.