Study On Deformation Law Of Coal-rock Mass And The Protection Range Of Under Underside Protective Seam

Exploitation of the protective layer has been increasing attention as a regional anti-surprise measures, generally, if conditions permitting protective layer mining regarded as the preferred anti-sudden measures. C13-1coal seam of pan-san mine with coal and gas outburst danger, in this case, select the B11-2coal seam as the first exploitation, through the mining-impact caused C13-1Coal pressure relief to reduce the risk of its prominence.Based on theoretical analysis, numerical value simulation and observation on the spot, the study concludes the laws of stress distribution and expanding deformation regarding the oblique working face of protected seam. The pressure-relief effect is obtained in the range of normal projection as regards the protected seam projecting roadway and wind roadway of protected seam’s working face, stress in the central section of oblique working face with a dramatically decline and a little change in the two sides of coal pillar. Also, coal seam occurs in expanding deformation. In particular, the central section of working face deforms a lot and two sides relatively small. The relative pressure-relief guide line of coal mass between the completely pressure-relief boundary (i.e. certain boundary of pressure-relief angle) and the normal projection of pillar edge(called oblique extending area) satisfies the request of protective seam exploiting. The area The normal projection between pressure-relief boundary and edge of coal pillar. This demonstrates that the expanding area still lies in its protected range. The widths of working faces regarding protective seam and protected seam are the similar with each other, i.e. inclining pressure-relief the angle can occur in change from acute angle to right angle90°.After study the mining-radius in extending area, we adjusted original design(bore-hole arrangement mode5X5m) to a better one(bore-hole arrangement mode10X10m).The new pumping scheme can largely reduce the number of bore-hole. The current study carries out an application test on exploitation of long distance lower protective seam in PanSan Coal Mine, HuaiNan, reduces the gas content of upper protected seam, eradicates the disaster of outburst coal seams and realizes their exploitation safely and effectively. According to the results of examination, relative expanding deformation is23.1%。, permeability coefficient is75times, the rate of gas extraction reaches40%, gas pressure falls from3.1MPa to0-0.7MPa and gas content from10m3/t to3.8m3/t after the deformation stabilization of upper protected seam C13in PanSan Coal Mine,HuaiNan. In addition, results have a reliability and rationality applying the ways of the theoretical analysis, similar simulation numerical value simulation, etc.Figure33table10reference50...