## 1 Introduction
### Analysis of Influence Range of Expansion Body Section
Stress diffusion: In terms of stress diffusion, the expansion bolt shows a better diffusion effect and the fixed range of the expansive body section to the loose circle is expanded by 45%. This effect helps to improve the overall stability of the anchor rod and reduce the risk of soil damage caused by stress concentration. However, due to  
Figure 12:8 The influence curve of the ordinary anchor rod on soil (yield area–time). the poor stress diffusion effect of ordinary bolts, the soil around the bolts may be more likely to be damaged. 3. The interaction between anchor and soil: The expansion anchor enhances the friction between the anchor and the soil during the expansion process, thereby improving the pull-out resistance of the anchor. This enhanced interaction helps to improve the stability and bearing capacity of the bolt. On the contrary, the friction between the ordinary bolt and the soil is relatively small, which may reduce its pull-out capacity and affect its performance in engineering applications. 4. Bolt deformation: From the simulation results, the deformation of the expansion bolt gradually increases with time, but the increase is small, showing good stiffness and stability. The ordinary bolt is prone to large deformation when it is subjected to force, which may affect its bearing capacity and engineering safety. 5. Bearing capacity: Due to the good interaction between the expansive anchor and the soil and the large contact area, the expansive anchor shows strong bearing capacity. This ability enables it to withstand large loads and is suitable for engineering applications that require a high bearing capacity. In contrast, the bearing capacity of ordinary bolts is relatively weak, and it is easy to be damaged when subjected to force. In summary, the expansive anchor is superior to the ordinary anchor in terms of stress distribution, stress diffusion, the interaction between anchor and soil, and the deformation and bearing capacity. These performance advantages make the expansion bolt have wider applicability and higher safety in engineering applications. However, the specific choice also needs to be comprehensively evaluated according to the specific requirements of the project and the geological conditions. Determination of Mechanical Parameters and Loose Circle Range of Bolt Surrounding Rock Soil in Numerical Simulation  
The determination of mechanical parameters is obtained from the core test taken from the site [44], and a part of the core is cut into cylindrical samples, one with a height of 100 mm and a diameter of 50 mm and one with a height of 20 and a diameter of 50. The core taken from each borehole is used to prepare 5 samples, with a total of four groups of 20 samples. The uniaxial compression test and Brazilian splitting are carried out on the samples, as shown in Figure 12:9  
Figure 13:0 Rock physical mechanics test. The physical and mechanical parameters of the surrounding rock measured by the test are shown in Figure 13:1  
The grouting body in the numerical simulation is generated by a Boolean operation of the soil and the hollow anchor, so that the grouting material is consistent with the soil material of the borehole itself, and so it is not pointed out in the table. Based on the field measured data of the 12,610 working face of the Hongshiyan Coal Mine in Huangling County, Yan'an City, Shaanxi Province (Figure 26), the range of loose circles was accurately measured by a CLC1000-Z ultrasonic surrounding rock crack detector. The measurement results are shown in Figure 27 and are used as parameters for numerical simulation analysis. The results of the loose circle measurement show that the radius of loose circles in Hongshiyan 12,610 working face is in the range of 0.6 m to 1.5 m, which can provide a reasonable reference for the design of an expansive body section.