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Combining with characteristics of Daqing and Xiajia 1.0m very contiguous seams combined mining and based on in-situ investigation and analysis of practical engineering, comprehensive research methods combining theoretical analysis, three-dimensional numerical simulation and in-situ mine pressure measurement were carried out to investigate the reasonable alternate distance, regularity of the overburden strata, technology of combined mining, complex stress field and displacement field, strata-pressure behavior.Firstly, through the analysis of the overburden strata movement, deformation failure process, collapse and the interactives space-time relation in the 1.0m very contiguous seams combined mining, the overburden strata structure forms of Daqing and Xiajia coal seams was obtained, and the conception of large and small double structure forms was proposed in the horizon of the lower coal seam roof. Based on theoretical calculation and scheme comparison analysis, the lower coal seam mining can only assign stable-pressure range which was formed in the upper coal seams goaf with conditions of the 1.0m very contiguous seams combined mining, and the reasonable alternate distance range of Daqing and Xiajia coal seams was obtained. The 1.0m very contiguous seams combined mining technology directly affected the reasonable alternate distance. Comprehensive combined mining technology of the upper mining overall height in one times and the lower caving coal was analysed. The supporting technology of roadway under the upper coal seams goaf was proposed. Through FLAC3D numerical simulation, stress field of surrounding rock and the lead abutment pressure influence on reasonable alternate distance were studied in the condition of 1.0m very contiguous seams combined mining, and it was also verified that theoretical analysis and calculation were reasonable.Lastly combining with the field geological condition, the characteristics of strata behavior, the lead abutment pressure of each mining gateway and deformation law of surrounding rock were studied through the in site measurement. Abundant mine pressure observation data was obtained.and results of theoretical analysis and numerical simulation were verified. Mine pressure observation results indicate that implementation effect of mining technology scheme and the reasonable alternate distance was excellent. The results of the study provide the theory reference and practical experience for very contiguous seams combined mining, and it also has practical meaning and reference value for very contiguous seams combined mining under the similar condition.
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