| The traditional coal pillar mining method is adopted in the third mining area of Hongjingta No.1 Coal Mine,the size of coal pillar is wide,the waste of resources is serious,and the semi-coal-rock roadway is used in mining roadway driving,which is difficult in construction and high in drivage cost.the roof type of the working face belongs to the hard roof,and the suspended roof is easy to occur after mining.In order to cancel the setting of coal pillar and reduce the driving rate of semi-coal-rock roadway with high construction difficulty and high cost,and to reduce the severe mine pressure behavior caused by hard roof caving after mining,the roof-cutting and pressure-relief non-pillar self-formed roadway mining technology was used to carry out research in 312 working face of the third mining area,using the methods of theoretical analysis,numerical simulation,field test and measurement.The application of roof-cutting and pressure-relief technology without coal pillar in semi-coal-rock roadway with hard roof is studied in the following aspects:(1)The general engineering situation of the test mine is introduced,and the technical principle and technological process of roof-cutting and pressure-relief self-roadway without coal pillar are briefly summarized.in addition,the principles and functions of the key technologies such as constant resistance large deformation anchor cable support technology,two-way concentrated energy tension blasting technology and surrounding rock support technology are theoretically analyzed,which provides basic engineering geomechanical data and technical data for follow-up numerical simulation analysis and field engineering test.(2)Through theoretical analysis,the overburden movement law of roof-cutting roadway technology is discussed,and on this basis,the mechanical model of roof subsidence is analyzed.The analysis results show that roof cutting along the roadway can increase the roof cycle to press the step distance,reduce the roof subsidence and maintain the stability of the roadway.(3)By using UDEC numerical simulation software,the evolution rules of roof displacement field,stress field and crack field in cut roadway are obtained.Secondly,the roof displacement of the stope near the cutting seam and the filling body retaining roadway along the goaf is compared and analyzed.the results show that the roof cutting roadway can enter the compaction and stable period more quickly.the slewing movement time,rotation angle and the severity of stope roof collapse of filling body are obviously greater than those of cutting roadway,and the surrounding rock of roadway roof and filling body are prone to rupture and instability under the action of high strength rotary deformation pressure.Thirdly,through the simulation results,the roof structure and caving characteristics of the end stope of the cutting roof,the uncut seam and the filling body retaining roadway along the goaf are summarized.Finally,the stress and displacement of the surrounding rock of the roadway formed by roof cutting and the roadway retained along the goaf are simulated and analyzed.the results show that the roadway caused by roof caving can effectively reduce the influence of dynamic pressure caused by roof caving,and the displacement of roof is small and controllable.the roof of the roadway has obvious pressure relief effect,the stress on the roof of the roadway is small,it is in the state of low stress relief,the stress concentration of the roadway is low,and the range of stress concentration is small.There is no slope deformation,and the roadway is always in a stable state.(4)According to the geological conditions of 312 working face of Hongjingta No.1Coal Mine,the key parameters used in the technological process of cutting roof roadway are calculated and analyzed by using the methods of theoretical analysis,field test and engineering experience,and the technical design system of cutting roof roadway is formed.The on-site monitoring of roadway roof subsidence,constant resistance anchor cable force,single force,stope hydraulic support force,roof rock swelling coefficient and surface subsidence are carried out.Under the condition of hard roof,the rock pressure behavior law and rock expansion law of self-formed roadway without coal pillar are obtained.the field monitoring results show that a series of roof-cutting and roadway protection measures can maintain the stability of the roadway along the goaf.The roof-cutting roadway technology can effectively protect the surface and restrain the surface subsidence.The field application effect also fully proves the feasibility of the roof-cutting roadway technology under the condition of hard roof semi-coal-rock roadway. |
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