Research And Application Of Extraction Technology In Fully Mechanized Face Of Fengjiata Coal Mine

The coal seam mined in Fengjiata Coal Mine belongs to shallow seam.There are two key strata in the roof of coal seam,and the periodic weighting phenomenon of working face is obvious.The step subsidence in the working face is serious and the roof management is difficult.Fengjiata Coal Mine has completed the withdrawal task of 12 fully mechanized mining faces,but in the withdrawal process of many working faces,roof fall and pressure frame accident occurred.The maximum of roof subsidence is 1 m,which leads to the support crushing and brings great difficulties to equipment extraction.In order to ensure the quick continuity of the working face,the overburden movement and rock pressure show law are analyzed by field measurement combined with theoretical analysis and numerical simulation,and the support scheme of withdrawal passage is put forward.The reasonable support parameters are explored and the selection method of withdrawal technology is discussed.It has certain significance to guide the safe withdrawal of the shallow coal seam in the last mining face.(1)Analysis of rock pressure law and rational application of yielding technology during the last mining period.Discriminate and analyze the weighting step of large and small periods through the measured resistance curve of the bracket in situ.The influence of advancing speed of working face on weighting step is studied.Based on the law of periodic roof weighting,the principle and application conditions of stopping mining yielding technology are introduced,and whether stopping mining yielding technology is applied in the end of 1209 mining face is reasonably judged.(2)Study on working resistance of support during pressure relief and withdrawal.During the last mining period,the overlying load of the stope is supported by the coal wall-support structure-support-goaf system,and the support is an important guarantee for the safe withdrawal.The dynamic failure characteristics of double key storey structure in roof are analyzed.The mechanical model of roof structure during stopping and withdrawing is established,and the reasonable working resistance that support should provide is determined.The scheme of strengthening temporary support during withdrawal is put forward.(3)Support design of withdrawal passage and optimization of equipment withdrawal scheme.Based on the timeliness of fracture development,the withdrawal scheme formulated by engineering analogy method is optimized,and the reasonable support parameters are determined by theoretical analysis and verified by simulation.Three kinds of equipment withdrawal schemes are proposed.Based on the distribution of plastic zone in surrounding rock and the curve of roof subsidence,it is determined that the optimal support design with two-way withdrawal has the best control effect on surrounding rock.(4)Field application of support design and withdrawal scheme.Field application results show that the surrounding rock control effect of optimized support design combined with bidirectional withdrawal scheme is good,and the normal continuity of mining face can be guaranteed.In order to verify the rationality of the supporting scheme and parameters,the FLAC3 D numerical simulation software is used to invert the roof movement rule and the supporting effect of the design scheme during the final mining period in the 2# seam fully mechanized mining face of Fengjiata Coal Mine.The withdrawal was completed safely,efficiently,economically and qualitatively with a cost saving of 1.07 million yuan.The research results can provide experience for other mines in Shenfu mining area.