Although permeation grouting technology has been widely used in engineering practice, there has not been sufficient research on how the distribution of pore sizes in porous media affects the diffusion of grout. In this study, based on the fractal theory of porous media and the Bingham fluid rheological equation, a Bingham fluid permeation grouting mechanism considering the distribution of pore sizes in porous media is proposed. The mechanism is validated through laboratory experiments and numerical simulations using COMSOL 6.0. During the experiments, parallel electrical resistance imaging is employed to monitor the diffusion range of the grout. Furthermore, the effects of grouting pressure, porosity, and water–cement ratio on the diffusion radius of the grout are analyzed. The results show that the Bingham fluid grout diffuses in a semi-spherical shape in the gravel. Additionally, parallel electrical resistance imaging can analyze the diffusion range of the grout in the gravel. The diffusion radius of the Bingham fluid grout in the gravel is smaller than the diffusion radius obtained by considering the particle size distribution theory, with an average difference of 31.8%. Compared to the diffusion radius obtained without considering the particle size distribution theory, the diffusion radius obtained by considering the distribution of pore sizes is closer to the experimental results. The numerically simulated program, which was developed for this study, can effectively simulate the diffusion law of the Bingham fluid in the gravel. So far, the Bingham fluid seepage grouting model considering the different particle size distribution of porous media has been built. The findings of this study can provide theoretical support and technical reference for practical grouting projects.

In view of the occurrence conditions of inclined coalbed, the deformation and failure characteristics of the main roof will affect the safe production of the working face. Therefore, the study of the deformation and failure characteristics of the main roof in the inclined coalbed has guiding significance for the control of surrounding rock. This paper takes the II1042 working face of Taoyuan Coal Mine as the research background, adopts the methods of theoretical analysis, numerical calculation, and field practice to analyze the evolutionary characteristics of the initial failure of the main roof of the working face under the background of the inclined coalbed, and explores the mechanical behavior characteristics of the working face roof during the mining of inclined coalbed. Based on the elastic thin plate theory, a mechanical model of the overlying rock roof of a large-angle coal seam is established, and the mechanical characteristics of the surrounding rock under the initial failure of the main roof under the unbalanced load are studied. The stress distribution characteristics of the lower surface are summarized, and the evolution law of the initial fracture of the main roof is summarized. According to the actual geological conditions of the II1042 working face of Taoyuan Coal Mine, the failure characteristics of the main roof and the initial breaking step distance are obtained by analysis, and the analysis results are verified by monitoring the mine pressure of each part of the target working face on site. The research results show that: ① Under the unbalanced load of the inclined coalbed, the deflection surface of the main roof of the coal seam is asymmetrical with respect to the arrangement direction of the working face, and the maximum deflection point is located at the upper middle position of the working face, namely (a/2, 1.836 b/π), and the main roof of the working face breaks for the first time when it advances to 35 m. ② With the advancement of the working face, the two long sides of the roof break first. With the deflection and deformation of the roof, the tensile stress in the middle of the main roof reaches the tensile strength of the rock and breaks, and then the two short sides of the roof break under the action of the breaking and turning of the rock, and the upper short side will break before the lower one. ③ According to the monitoring and analysis of the rock pressure at each part of the working face, it is judged that the initial pressure step distance is between 28.2 m and 34.6 m, which is consistent with the theoretical analysis results.

For the thick alluvium and thin bedrock coal seam mining in East China, it is easy to produce water by pressing the frame. Taking the engineering geological conditions of the thin bedrock coal seam 1611 (3) working face in the Zhangji Coal Mine of Huainan Mining Group as the research background, the breaking law of the thin bedrock coal seam working face with thick alluvium was studied by using a similar material physical simulation experiment and theoretical analysis. It is revealed that under the load transfer of the loose aquifer, the roof fracture of the stope with thick alluvium and thin bedrock is characterized by large and small periodic ground pressure, and the combination failure of the high key stratum and the low key stratum with large cycles is prone to support crushing accidents. Based on this, the safety mining technical measures of reducing the fracture distance of the high key stratum by forced roof caving are proposed, and the reasonable blasting parameters are calculated. After field application, no support crushing accident on the working face was recorded, and the mining was safe, which provides a technical reference for the mining of the working face under similar conditions.