Research On Directional Caving Technology Of Roadway Side Roof Based On Stress Field Intervention

The gob-stayed roadway is an important guarantee for continuous mining without coal pillar,increasing coal recovery rate and reducing roadway drivage rate,and is also one of the key technologies to solve gas and power disasters and realize coal scientific mining.However,along the gob-side roadway is in the goaf edge,during the service of the roadway will be affected by multiple mining dynamic pressure,its overlying strata structure stability and roadway surrounding rock deformation control is seriously challenged.In view of the serious deformation of the gob-side roadway,the surrounding rock control is mainly taken to strengthen the roadway and the roadway offshoot protection or to the roof of the mining goaf to crack the top and pressure,while the use of fire-work products in high gas mine has many limitations,this paper creatively puts forward the combination of static rock breaking technology and top pressure unloading technology,and carries out related research work.Through the comprehensive research means of theoretical analysis,numerical simulation and industrial experiment,this paper analyzes the movement characteristics of overlying strata along the gob-side roadway,focuses on the study on the roof structure of the gob roadway,and puts forward the transfer bearing mechanism of the roof in the "inverted trapezoid" bearing area of the gob-side,and the basic roof of the mining-side is on the solid coal side.Different mechanical models are constructed for three different faults in the upper and gob side of the roadway,and it is found that no matter where the fault position is located,the load on the roadway offshoot protection is greater when the length of the cantilever structure is longer in the foundation roof strata.Therefore,adopting relevant technical means to reduce the length of the cantilever structure of the basic top-stope can effectively reduce the load of the alley offshoot.Therefore,the advanced working face construction drilling and injecting static crushing agent static cutting top,the interference of the original stress balance state in the roof strata,the directional collapse along the direction of the drilling line under the influence of the mining dynamic pressure in the face,the active control of the roof strata movement can effectively alleviate the problem of high stress of surrounding rock in the gob-side roadway.In order to optimize the surrounding rock stress environment and structure shape of the roadway,the deformation time of surrounding rock along the goaf is shortened,which is helpful to the stability of the surrounding rock of the left roadway.Using the method of the hole charge,through the analysis of the stress of the borehole surrounding rock and the crack expansion analysis combined with the field practice,it can be seen that when the diameter of the drilling hole is900 mm,the rock mass may be cracked after the static breaker reaction;Through the numerical simulation analysis of the FLAC3 D,it is known that the height of the top should be cutting top angle should be taken 70° suitable;no matter what kind of fracture form the basic top of the gob stays in the top of the cut,the offshoot resistance ratio of the gob-left roadway is reduced when the top is cut,and finally the related drilling and charging construction process and the mine pressure observation plan are designed.With the combination of the mining side cutting top unloading and thestatic rock breaking technology,the static cutting of the front face and the influence of the mining dynamic pressure in the face can realize the directional collapse of the basic roof along the gob-side roadway to reduce the deformation of the surrounding rock and achieve its stability.The research enriches the construction method of jacking and unloading,which has a certain theoretical and practical significance.