The causes of the size effect (SE) and loading rate effect (LR) for rocks remain unclear. Based on this, a gypsum-mixed material was used to simulate sandstone, where the dosing ratio was 7.5% river sand, 17.5% quartz, 58.3% $\alpha$-high-strength gypsum, and 16.7% water. The specimens were designed to have a height-to-diameter ratio (HDR) of 0.6~2, and three strain rates (SRs)—static, quasi-dynamic, and dynamic—were used to perform single-factor rotational uniaxial compression experiments. PFC^2D was used to numerically simulate the damage pattern of a sandstone-like specimen. The results showed that the physical parameters did not change monotonically, as was previously found. The main reason for this is that the end-face friction effect (EFE) is generated when the dynamic SR or the HDR is 0.6~1, with a damage pattern of “X”. Under mechanical analysis, the power consumed by the EFE was inversely proportional to the HDR and directly proportional to the LR, and it can reduce the actual amount of energy transferred inside the specimen. This paper may provide a foundation for the study of non-linear hazards in coal and rock.

The dynamic load generated by the fracture of a hard roof significantly disturbed the stability of the surrounding rock in the lower roadway of the study site. This study established a dynamic transmission model of hydraulic fracture mesh and analyzed the influence of the hydraulic fracture mesh parameter on dynamic load attenuation from the perspectives of energy distribution and stress wave attenuation. The SHPB numerical model was established and calibrated based on PFC2D, and the findings were as follows: the hydraulic fracture mesh changes the rock into a discontinuous structure, which hinders the propagation of dynamic load and changes the medium of dynamic load propagation, resulting in part of the dynamic load being reflected and accumulating in the mesh area, causing the rock in the mesh area to break up or making the rock on the side of the hydraulic mesh to slip, which reduces the energy of the dynamic load. Finally, an industrial experiment was conducted on the 10107 working face of Huayuan Coal Mine. Monitoring results showed that the deformation of the roadway sides and roof was reduced by 833 mm and 861 mm, respectively, and the stability of the surrounding rocks of the roadway was effectively improved.