| In the coal mining process,part of the working face roof collapsed naturally with the mining face.When the roof is hard,under the support of a single-sided coal pillar,part of the rock layer above the roadway of the face fails to collapse in time,resulting in a suspended roof in the goaf.The suspended ceiling needs a long time to turn and sink to collapse itself.The collapse of the cantilever roof affects the dynamic pressure caused by the narrow coal pillars along the roadway for a long time,and the roadway is difficult to support.In order to alleviate the tension of mine excavation and replacement,improve the recovery rate of the working face,and reduce the maintenance cost of the roadway,according to the geological conditions of the working face of 16021 and 16031 in Zhaogu No.1 Coal Mine,the cutting roof pressure relief technology is adopted in the 16021 return air lane,and the goaf is adopted The way of the roadway is 16031 Huifeng Roadway.The following research results have been achieved:(1)Through research on the directional fracture control blasting and cutting technology of D-shaped energy gathering tube,it is determined that the distance between the on-site blasting hole position and the coal pillar S?500mm,the borehole inclination angle ??75°,the angle between the borehole and the vertical direction ?=0 °,cutting height 22.8m,drilling depth 23.7m,drilling diameter 50 mm and drilling spacing 500 mm.The directional slit tube is used to control the formation of the pre-splitting slit surface,and the mine three-stage emulsified explosive is used.The diameter of the explosive is?=32mm,the length l=200mm,the weight m=200g;the uncoupling coefficient K=1.6;The dose is 4.8kg.(2)In order to analyze the influence of different fracture positions of the basic roof on the stability of coal pillars,based on the mechanical model of surrounding rock structure along the roadway,eight types of fracture structures were analyzed,and the calculation formulas of eight types of fracture structures were derived.Through the above analysis,we can grasp the stress of coal pillar under the basic roof fracture structure.(3)Through the analysis of the cross section shape of 16031 return air roadway and the distribution law of lateral support and supporting pressure,a reasonable roadway support design is adopted.The anchor rod adopts long L=2400mm,diameter ?=22mm,left-handed,non-longitudinal threaded steel anchor rod,anchor rod spacing D?1.2m,anchor cable length L=8.3m,anchor cable spacing 1.6m,1.8m Three at the top of each row.The method of arranging the monitoring points for surface displacement monitoring is the "cross point method".Through the analysis of the changes of the tunnels at multiple stations,it was found that the roof and floor of the tunnel at the beginning,the changes of the two gangs are relatively small compared to the rear stations,and the pressure of the roof and the two gangs are also small.The advancement of the working surface gradually became larger.This study provides a reference for the research on the mechanism and related parameters determination method of cutting and pressure relief along goaf under thick and thick layers with high stress. |
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