Analysis of surrounding rock stability and key influencing factors in the goaf area of special-shaped roadway

Aiming at the special-shaped mining roadway of No.5 coal seam in coal mine, the calculation formula of the empty roof distance of the special-shaped roadway is obtained based on the thin plate theory, the influence law and weight of different factors on the empty roof distance are analyzed, and the influence law of the key factors on the deformation characteristics of the surrounding rock and the vertical stress distribution in the empty roof area is analyzed by FLAC^3D numerical simulation.The results show that the stability of the roof in the goaf area is related to the roadway width, vault height, tensile strength and roof load, among which the roadway width and sheet thickness are the key factors.The theoretical maximum empty roof distance of special-shaped roadway is determined to be 3.653 m, and the actual maximum empty roof distance is 3 m after considering the safety factor.Numerical simulation to determine the reasonable support strength and the maximum horizontal stress distribution direction consistent with the roadway direction can provide favorable conditions for rapid tunneling.In the field application of 3X51S heading working face, the empty roof distance reaches about 2-3 m, which improves the excavation speed, and the maximum displacement after the roadway is stable does not exceed 100 mm.