Study On Control Surrounding Rocks Deformation By Boreholes Destressing Of The Mining Gateway In "Three-soft" Coal Seam

With the increase of mining depth and the complexity of mining conditions, many mining areas have appeared a question of that the traditional supporting method is difficult to control high stress soft rock roadway, exploring the reasonable support form and support parameters of soft rock roadway becomes an urgent problem. Based on the domestic and foreign research existing state and the geological condition of Yong Hua mine, in view of the traditional support have helpless predicament to the three soft coal seam roadway, proposed control surrounding rocks deformation by boreholes destressing, implemented destressing boreholes between the U-steel after the erection U-steel, and absorb the roadway surrounding rock deformation and reduce stress by the destressing boreholes. This paper analyzed the volume change due to dilatancy and strain softening by elastic-plastic theory, so as to determine the parameters of boreholes destressing. By FLAC3D numerical simulation software to analyze deformation of the surrounding rock in tunnel and stress transfer function by boreholes destressing, after the implementation of boreholes destressing, the surrounding rock deformation reduced, the high stress move deeply in the rock-mass and the roadway in the stress decreasing zone, at the same time, analyze borehole diameter, borehole length and borehole distance effect on the pressure relief, while the longer length, the larger diameter, the smaller array pitch, the better of the borehole relief, and more conducive to the stability of the roadway. At last carry on the engineering test in Yong Hua mine, controlled the fierce distortion and continued creep of this roadway effectively, and this support plan is simple, convenient, and the production requirement is satisfied.