In this study, taking the Sheng’an coal mine as an engineering background, the failure characteristics of the surrounding rock of a roadway under repeated mining in a close-distance coal seam is comprehensively illustrated through field measurements (e.g., drilling imaging), theory analysis and numerical simulation (finite difference method (FDM)). The results show that although the return airway 10905 remains intact, the apparent failure of the roadway’s roof and the coal pillar can be observed. In addition, the expression of floor failure depth caused by upper coal seam mining is obtained through elastic-plastic theory. Meanwhile, the deformation of the surrounding rock of the roadway increases with the increase of repeated mining times, especially for the horizontal displacement of the roadway on the coal pillar side. Moreover, the cracks’ evolution of surrounding rock in the roadway can be observed as asymmetric characteristics. Finally, the stability control technology of “asymmetric anchor net cable + I-steel” is proposed to prevent potential mining disasters, and the feasibility of this support scheme is verified by numerical simulation and field practices. It can meet the requirement of safe mining and provide guidelines to effectively solve the failure of a roadway in close-distance coal seam mining.

In order to effectively solve the problem of gas concentration overrun in the upper corner of goaf and tailentry during the mining of panel 9303 in Anshun Coal Mine, based on the advantages of controllable trajectory and wide coverage area of directional drilling technology, high directional long boreholes are arranged in tailentry 9303 to extract pressure relief gas. Firstly, the principle of high directional long borehole drainage technology is introduced, and the fracture evolution of overlying strata is obtained through using numerical simulation, theoretical calculation, and field practice, and the fracture evolution range is determined to be 6–12.69 m, and rationality of fracture height obtained by theoretical analysis and numerical simulation is verified by the method of field borehole peep observation. Through the analysis, it is concluded that the best location of the final hole is within the range of 6–12.69 m of the roof of coal seam 9#. The field practice has proved that the final hole position of the high directional long borehole is arranged at 12 m from the roof of coal seam 9#, and the average gas extraction concentration can reach 40%–50% after the borehole enters the stable extraction stage, the purity of gas extraction is up to 8.5 m³/min, and the gas concentration in the upper corner of panel 9303 is stable below 0.5% during mining, which achieves good gas drainage and control effect and provides a new way for gas control under similar geological conditions.

In order to analyze the influence degree of different factors on gas extraction radius, on the basis of coal seam gas flow theory and elastic mechanics, considering the influence of coal seepage rate change on gas flow, the COMSOL Multiphysics numerical simulation software is secondarily developed by using the stress-seepage coupling mathematical model of coal and rock containing gas. Taking coal seam No.2 of Juji Coal Mine as an example, the effective extraction radius under different extraction negative pressure, extraction borehole diameter, extraction time, and initial permeability of coal seam are simulated, respectively. Then, the orthogonal test method is used to design different calculation schemes, and the effective extraction radius is used as the judgment index. The simulation software is used to calculate the effective extraction radius corresponding to different influencing factors. SPSS statistical software is used to analyze the parameters. The multivariate linear regression equation of the influencing factors of the effective extraction radius is obtained, and the multivariate linear regression model is established. The results show that the negative pressure of extraction has little effect on the effective extraction radius; the effective extraction radius gradually expands with the increase of extraction time and extraction aperture, but it has certain timeliness. The initial permeability of the coal seam has a great influence on the effective extraction radius. The influence degree of different influencing factors from large to small is the initial permeability of coal seam, extraction time, borehole diameter, and extraction negative pressure. Therefore, the key to improving the effectiveness of gas extraction is to increase the initial permeability of the coal seam before preextraction, ensure sufficient extraction time, appropriately increase the borehole diameter, and improve the negative pressure of extraction. Finally, the gas flow rate is used for a field test, and the measured results are basically consistent with the simulation results, which proves the correctness of the mathematical model of gas-containing coal and the feasibility of using numerical simulation methods to study the effective extraction radius of coal seams.