## 3 Results  
### Stress-Strain Curve of Anchor Solid  
The axial stress-strain curves during uniaxial compression of the specimens with different grain sizes are shown in Figure 6. Compared with the unanchored specimen, it can be seen that the residual strength value of the anchored specimen in the late stage of damage had a greater increase, but the residual strength value in the compression process of the 2-4 mm grain size aggregate specimen was higher than that of the 4-8 mm and 10-15 mm grain size aggregate specimens. Consequently, the trend of the stress-strain curves of the larger aggregate specimens close to the horizontal direction was more obvious. This indicates that under uniaxial compression conditions, anchors can increase the compressive strength and elastic modulus of specimens. They can also improve the residual strength of the rock mass, but the ability of the anchor bar to improve the residual strength of the rock mass gradually decreases with the increase in the specimen crushing degree. Comparing the stress-strain curves of the different types of anchored specimens and unanchored specimens revealed that the anchors change the deformation characteristics of the surrounding rock body. Under the no-anchor condition, the brittle characteristics of the rock-like body specimens were more obvious, and when the specimen reached the peak strength, i.e., when the specimen reached the limit of its ability to resist the external load, the rate of decrease in the stress-strain postpeak curves was faster, and the postpeak modulus was larger. For the anchored specimen, its brittle characteristics were not obvious, and the deformation of the anchored rock body showed plastic characteristics. When the anchored rock sample reached the peak compressive strength, the peak stress-strain curve began to decline. Compared to the unanchored specimen, the stress decline rate was reduced, and when the stress dropped to a certain value, the stress-strain curve of the specimen had a small fluctuation, that is, the specimen stress decline rate was small with regard to the anchor at this time. The role of the anchor was more obvious. There was no-anchor specimen in the load loading process. When the specimen reached the peak compressive strength, the rate of stress decline was faster. When the anchor specimen reached the peak strength in the rupture process, the anchor bar prevented internal cracks from expanding and penetrating inside the specimen, thus slowing down the rupture rate. Figure 5: Test setup and specimen loading. The uniaxial compressive strength of the specimens with quartz sand of different grain sizes as the aggregate showed significant differences. These specimens had a smaller surface area for the smaller grain size quartz sand aggregate, a smaller contact surface for gypsum, and the formation of structural surfaces of smaller sizes inside the specimen with a smaller degree of fragmentation, while they also had a larger surface area for the larger grain size quartz sand aggregate, a larger contact surface for gypsum, and the formation of structural surfaces of larger sizes inside the specimen with a higher degree of fragmentation. The change characteristics of the compressive strength and elastic modulus of the rock mass under the conditions of the different grain sizes and anchoring methods are shown in Figure 7. It is worth explaining that the modulus of elasticity of the rock mass in the test is the slope of the approximate straight line segment of the axial stress-strain curve, i.e., the generalized modulus of elasticity, as can be seen from the diagram:  
1. The uniaxial compressive strength and modulus of elasticity of the specimens showed the following pattern: small-size aggregate specimen > medium-size aggregate specimen > large-size aggregate specimen.