Deformation and failure mechanism of the surrounding rock of the floor roadway under the influence of working face mining is complicated, and roadway control is difficult. The floor roadway of the 11123 working face in Pan’er Mine is taken as the research object of this study based on semi-infinite body theory of elastic mechanics to establish a mechanical model along the advancing direction of the working face and derive the stress expression of any point in the affected area of floor mining. According to the theoretical results, effective reinforcement and support schemes are then proposed. FLAC3D numerical simulation analyzes the stress and deformation of the surrounding rock of the floor roadway before and after the reinforcement. The numerical simulation results showed that (1) mining abutment pressure of the overlying working face forms a certain range of stress concentration on the roof and two sides of the roadway and will cause deformation and damage to the floor roadway and (2) overall bearing capacity of the surrounding rock of the roadway is significantly improved, and surface displacement of the floor roadway is reduced by 64 mm through the reinforcement and support of the floor roadway. On-site monitoring data of the floor roadway in the 11123 working face of Pan’er Mine showed that the maximum displacement of the roadway roof and two sides is controlled at approximately 80 mm, and the surrounding rock deformation of the roadway is appropriately controlled to meet the needs of safe production.

Aiming at the mining disaster of a thick hard roof, based on the analysis of the mining instability influence of the thick hard roof, this study constructs the mining bearing mechanical model of the thick hard roof by using mechanical theory and obtains the mechanical distribution equation of mining bearing and energy accumulation, the mining instability energy release equation, and the dynamic load response equation of a hydraulic support in the working face, as well as the dynamic load response characteristics of the hydraulic support in the working face, putting forward the technical countermeasures for the strong dynamic pressure control of the thick hard roof in the working face. This research shows that 1) the larger the overburden load and suspension span of the thick hard roof, the more serious the mining bearing state and energy accumulation evolution; the greater the rock thickness and elastic modulus of the thick hard roof, the greater the flexural stiffness of the roof, resulting in the increase of the roof mining limit breaking span, which indirectly aggravates the mining bearing state and self-energy accumulation evolution; 2) the dynamic support resistance of the hydraulic support is composed of the dynamic support resistance caused by the release of elastic energy accumulated by mining of the thick hard roof, the work done by the overlying load, and the static support resistance caused by the direct roof gravity; 3) the dynamic support resistance caused by the work of the overlying load accounts for the highest proportion, followed by the dynamic support resistance caused by the release of mining elastic energy by the thick hard roof; the cause of mining instability and the strong dynamic pressure of the thick hard roof lie in the large span of the mining suspended roof, and the large-scale mining suspension structure of the thick hard roof leads to a high overlying load and large accumulated energy; and 4) the mining instability of the thick hard roof leads to a strong dynamic load response of the hydraulic support; adopting pre-splitting and roof cutting technology to reduce the breaking span of the thick hard roof and reducing the impact dynamic load caused by mining instability of the thick hard roof can effectively eliminate the potential safety hazard of overlimit bearing of the hydraulic support.

Mine pressure at the working face is severe due to it being directly covered by a thick hard roof. To further investigate the technology of controlling the mine pressure of a thick hard roof, the upper working face of 13,121 in Gubei mine of Huainan mining area was used as the engineering background, and similar simulation experiments, mechanical analysis, numerical simulation, and engineering applications were used to obtain the structure of a pre-cracked cut roof cut falling body, as well as establishing the mechanical model of hydraulic brace support resistance and direct covering. The results of the numerical simulation combined with the 20 m step pre-cracked top cutting showed that the cantilever length of the roof plate in the mining area was shortened by 25.61%, the stress concentration was reduced by 31.74%, and the stress level of the hydraulic brace was reduced by 26.59–28.38%, destroying the integrity of the thick hard rock body. According to the field monitoring data analysis, the working face’s initial pressure step and periodic pressure step were reduced, and the average dynamic load coefficients of the initial pressure and periodic pressure were 1.43 and 1.33, respectively, with a small dispersion of the dynamic load coefficient of the bracket. The pressure at the working face is regulated, and the chosen support equipment, in conjunction with the roof cutting scheme, can meet the thick hard roof’s support needs.

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