Research On Support Technology Of Soft Rock Access In Zhongguan Iron Mine Access In Zhongguan Iron Mine

The site conditions of the entry in Zhongguan Iron Mine are complex,and the rock joints and fissures of the orebody are developed,and the soft rock is cemented.In the process of excavation,there are some problems,such as serious ground pressure,large deformation and high difficulty of support.The main characteristics of these problems are side-wall extrusion,roof support subsidence,bolt shedding,arch frame damage,high support cost and high repair rate.The above problems in roadway support of Zhongguan Iron Mine have become a major technical problem affecting mine production.Ensuring the stability and safety of roadway is the basis of safe and efficient production in underground mines.In order to realize the scientific support of the approximate roadway,ensure the safety of the approximate roadway and improve the economic effect of the mine,this paper takes the Zhongguan Iron Mine-230 m level approximate roadway as the research object,and adopts the method of field investigation,theoretical calculation and simulation numerical value.In this paper,a systematic study is carried out on the supporting problems existing in the roadway.Mainly completed the following three aspects of research work:(1)the stability classification of the surrounding rock of the roadway is studied.Based on the field investigation and pole diagram of surrounding rock structure plane,the structural features and completeness of surrounding rock are analyzed,and it is concluded that the structural plane is easy to fall and the surrounding rock of roadway is difficult to form self-stabilization.Most of them are unstable.Therefore,combined support is suitable for surrounding rock roadway in Zhongguan Iron Mine,and high strength support parameters are suitable.(2)field investigation and analysis of roadway support status and damage situation.Field investigation shows that the main failure modes of surrounding rock support in mining roadway are local surrounding rock failure,shear failure,tensile failure,shear failure and composite failure,and tidal expansion failure.The main reasons are natural and human factors.Based on the mechanism analysis,the original support scheme is suitable for the surrounding rock properties,but the support strength design is insufficient,so the support parameters need to be optimized.(3)numerical simulation of surrounding rock and selection of optimal parameters.Numerical simulation can better demonstrate the failure process of ore and rock.Orthogonal test can reduce the number of tests.Combining the two methods,the optimum support parameters are determined according to the displacement of side wall,roof and volume of plastic zone.When the soil thickness decreases from 200 mm to 100 mm and the spacing between steel arch frames decreases from 1.0 m to 0.5 m,the support simulation effect is the best.According to different geological conditions,the optimum supporting parameters are selected,that is,the length of bolt is 2.4m,the thickness of concrete shotcrete is 100 mm,and the spacing of telescopic metal arch is 0.5m.The industrial test proves that the optimized scheme can improve the supporting effect greatly compared with the original one.The scheme can adapt to the surrounding rock conditions,provide sufficient supporting strength and ensure the production safety.Theoretical research and practical application show that the optimized support scheme proposed in this paper highly adapts to the surrounding rock properties of Zhongguan Iron Mine,effectively solves the shortcomings of the original support scheme,can ensure the safety of the roadway,and can meet the needs of mine production.