Study on deformation and stress evolution law of surrounding rock under repeated mining in close coal seam.

Aimed at the problem that the mining roadway is seriously affected by the repeated mining under the up-down successive cooperative mining mode, this paper takes Qiuci Coal Mine as the research background. Based on analysis of mining influence stage of A502 haulage roadway, the stress evolution and deformation law of surrounding rock of roadway are analyzed through similar simulation, the principle that the ratio of main stress affects the stability of roadway under the influence of repeated mining is obtained based on the plastic failure theory of surrounding rock of roadway, the roadway stability control method by periods and stages is put forward based on the principle of roadway stability control, and the numerical simulation scheme is designed to determine the reasonable coal pillar width and support mode of roadway. The results show that the coal pillar with the width of 8 m can reduce roof stress of roadway by 38.4% and 64.3% during the tunneling period and period after formation of roadway, and the principal stress ratio is reduced to 2; the stability of surrounding rock during and after excavation can be guaranteed by adopting <italic>φ</italic>20 × 2400 bolt and advanced hydraulic support. Through field measurement, the maximum deformation of A502 haulage roadway is only 60 mm, and the cumulative output of coal during the period of mining influence is 1,833,700 tons, thus the safe mining of coal mine is realized, and enormous economic benefits are generated. [ABSTRACT FROM AUTHOR]