## 5 Experimental Results
### Generalization and Analysis of Destructive Modes  
Under step-by-step loading, the surrounding rock of the anchorage mainly exhibits deformation along the axis, and the deformation laws of the free face, front anchor face, and rock mass between anchors follow the above trend, and the deformation is also relatively stable, as shown in Figure 16. The deformation of the rear anchor surface is relatively disorderly. The deformation of the rock mass between anchors shows a sudden increase after the load is increased to 8 times the design load, as shown in Figure 16a. The deformation of the rock mass on the free face also shows a sudden increase at 8 times the design load, as shown in Figure 16b. The sudden increase in deformation of the rock mass on the front anchor surface occurs at 9 times the design load, as shown in Figure 16c. The sudden increase in the deformation of the rock mass on the rear anchor surface occurs at 7 times the design load, as shown in Figure 16d. From the analysis of the deformation trend, the critical load for anchor failure is 7 to 9 times the design load.  
Under step-by-step loading, the deformation of the rock mass between anchors can be continuously monitored, and analyzing the failure mode of the anchor based on its deformation is more accurate. The boundary point of deformation is located at a depth of 6.2 m on the front anchor face, and the rock mass with a depth of more than 6.2 m shows a relatively uniform horizontal deformation, which is more obvious at 5 times the design load, as shown in Figure 17a. The boundary point of deformation is at a depth of 6.5 m on the rear anchor surface. The rock mass at a depth of 3.5-6.5 m shows obvious horizontal displacement, which is very obvious at 7 times the design load. Above a depth of 3.5, it shows deformation on the rear anchor surface and shows a certain inclination, as shown in Figure 17b.  
Figure 15: Dislocation meter deformation curve. (**a**) Deformation curve under different loads; (**b**) dislocation meter F9 deformation curve; (**c**) dislocation meter F8 deformation curve; (**d**) dislocation meter F1 deformation curve.  
From the analysis of the inclined hole, it can be seen that the front anchor face with a depth of more than 6.2 m exhibits relatively uniform horizontal deformation, and the greater the load, the more uniform the horizontal deformation. This area should be located before the fractured surface. The upper part of the rock mass on the rear anchor surface is inclined backwards, so the surface fracture surface should be located between holes C1 and C2. The rear anchor surface C1 undergoes significant differential deformation at a depth of 3.5 m, which should be near the rupture surface. In summary, connecting the two feature points with the rear anchor surface point essentially forms the shape of the rupture surface. Similarly, connecting the lower feature points forms the lower rupture surface, with an upper rupture angle of about 35\({}^{\circ}\) and a lower rupture angle of about 40\({}^{\circ}\). The rupture surface is trumpet shaped and cut out from the free face in an arc shape, as shown in Figure 18a.  
Figure 16: Deformation curve. (**a**) Deformation curve of surrounding rock between anchors under step load; (**b**) deformation curve of free surface under step load; (**c**) deformation curve of front anchor surface under step load; (**d**) deformation curve of rear anchor surface under step load.  
From the perspective of damage zoning, it can be mainly divided into displacement zones and disturbance zones. The upper displacement zone is dominated by tensile shear damage, while the lower displacement zone is dominated by compressive shear damage, as shown in Figure 18b.