Study On Deformation Law Of Overlying Roadway And Supporting Technology Optimization Under The Condition Of Lower Protective Seam Mining

Aiming at stability of surrounding rock control of the upper mining roadway during the working face mining which is layout in the lower protective coal seam, and with the background of the SHANJIAOSHU Mine, this paper conducts the research on the mining influences of the 18# working face mining in the lower protective layer on coal roadway arranged in the upper 15# coal steam. It makes an in-depth systematic study of the deformation law of the upper coal roadway by theoretical analysis, numerical simulation and site monitoring. Based on the research achievements, it conducts an optimization study of the supporting technology of the upper coal roadway and launches a site engineering application, which obtains satisfactory results. The following research results were obtained:(1) This paper has studies the deformation law of the overlying strata when the lower protective coal seam is exploited. The time and space relationship between the stress distribution of mining over burden rock, movement deformation characters and mining influence has been detailed analyzed, and a mechanical model of overburden deformation under the influence of the mining has been built.(2) Based on the above research, with the background of SHANJIAOSHU, the deformation laws of the overlying strata when the lower protective coal seam is exploited have been specific analyzed. Through the calculation, the height of cave zone of the protective coal seam is 5.69~6.09 m, the height of fracture zone is 29.05~41.31 m, and the upper coal seam which is protected is in the middle-upper part of fracture zone, and the 22155 coal roadway in the upper coal seam is in the area of stress concentration.(3) It adopts the numerical analysis software FLAC3 D to make a numerical simulation on the influence of the lower protective strata to the overlying coal roadway. In the process of the lower protective working face mining, there is area of stress concentration in the roof and floor of upper coal seam. The roof broken forms is mainly caving, and the floor is mainly heaving. When the distance between the upper coal seam and the lower protective working face is closer, the damage of the roof is more seriously, but the heaving of the floor is relief.(4) It makes an in-site monitor and analysis of the actual mining influences of the roadway which is in the affect region of the lower protective working face advanced, the results show that, the range of the abutment pressure is about 55 m, thus the reinforce support of the upper coal seam should ahead of the working face 60~75m.(5) According to the results of theoretical analysis, numerical simulation and site monitoring and the problems in the pre-existing mining support, it makes optimization of the supporting of the overlying coal roadway and redesigns the scheme. The optimized supporting technology and scheme has had the practical engineering application under the similar mining conditions and achieved good supporting effect.