# Research on the Self-Drilling Anchor Pull-Out Test Model and the Stability of an Anchored Slope
## 5 Conclusions  
This study, based on the reconstruction project of an abandoned open-pit mine in Dalian, systematically analyzed the anchoring performance and reinforcement effects of self-drilling anchors in a strongly weathered dolomitic limestone layer using a combination of field pull-out tests and FLAC3D numerical simulations. The main conclusions are as follows:  
1. The experiments revealed that, under the conditions of grouting pressure at 0.8 MPa and a water-to-cement ratio of 0.8, the average interface bond strength between the self-drilling anchor and the strongly weathered dolomitic limestone reached 0.147 MPa, significantly higher than the recommended value for this stratum (qsk = 0.12 MPa). The test results indicated that the interface shear stress along the anchorage section showed an exponential decay along the axis, with the effective bearing area concentrated near the anchor's proximal end. The longer anchorage sections reduced randomness due to spatial averaging effects, but the bond strength showed a de  
Figure 28: Maximum shear strain increment and velocity vector diagram of the slope before and after support. creasing trend as the anchorage length increased, validating the \"effective anchorage length\" theory;
2. By incorporating a residual strength model to modify the pile unit in FLAC3D, a more realistic anchorage analysis model was developed. The modified model accurately reflects the nonlinear decay of anchor axial force with depth and the spatial distribution characteristics of interface shear stress. The simulation results closely matched the experimental data, with an error in the ultimate pullout capacity of less than 6%;
3. Numerical simulation analysis based on orthogonal experiments showed that anchor length, installation angle, and spacing significantly affected slope stability. Considering both safety and economic factors, it is recommended to use an anchor length of 7 m, an installation angle of 30\({}^{\circ}\), and a spacing of 2 m as the support scheme, which results in an increase in the safety factor to 1.303 and an anchor consumption of 59.5 m/m. After the support, the maximum horizontal displacement of the slope decreased from 8.197 cm to 4.408 cm, and the maximum shear strain increment was reduced by 52.6%, significantly inhibiting the development of potential sliding surfaces. Finally, we would like to emphasize the limitations of this work and the directions of our future research:  
1. As the selected working conditions in this paper are highly weathered dolomite strata, which are relatively special, it is currently impossible to determine whether self-drilling anchor rods can have the same or better anchoring performance in other similar geological conditions. Therefore, in our next research, we will conduct studies on the anchoring performance of self-drilling anchor rods under different stratum conditions and multi-layer soil conditions and carry out numerical simulation analysis based on anisotropic stratum conditions. At the same time, the performance degradation of self-drilling anchor rods under the influence of seismic loads is also under consideration in our subsequent work;
2. The modified pile element does indeed have a good simulation performance in the simulation, but at the same time, the size effect of the anchor rod will also have a certain impact on the overall anchoring performance. Therefore, it is possible to attempt to use the Zone element combined with the interface method to study the overall anchoring performance of the anchor rod. J.L. : Provision of ideas and methods. X.Z. : Manuscript writing, numerical simulation work, and data processing. G.L. : Optimization of image tables and Supervision. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Some or all data that support the findings of this study are available from the corresponding author upon reasonable request. The authors declare no conflicts of interest.