# Landslide-Tunnel Interactions and Control Countermeasures under an Orthogonal System
## 5 Conclusions  
This study examines the interaction between tunnels and landslides. The failure modes of three different tunnel and landslide positions are analyzed, and a numerical model is established for the typical characteristics of tunnels located on landslide surfaces. We used numerical simulation software FLAC3D 6.0 to summarize the failure deformation characteristics and displacement deformation law of a tunnel under the influence of a landslide. Additionally, the control effect of anti-slide piles on the deformation of the rock surrounding the tunnel is analyzed. Our conclusions are as follows:  
1. Based on the relative positional relationship between the tunnel and the sliding surface, the failure modes of tunnel landslides in three different positions are summarized. These are located in the landslide mass, the sliding surface, and the sliding bed. Tensile failure and shear failure often occur at different stages of tunnel-landslide interactions. Tunnel deformation and landslide deformation exhibit mutual influences in both temporal and spatial distributions.
2. A numerical model of the tunnel on the sliding surface is established. The plastic zone failure, surrounding rock stress distribution, and displacement distribution of a tunnel under the influence of a landslide are analyzed. The simulation results show that, under the influence of a landslide, there is large plastic zone damage on the  
Figure 18: Variations in the deformation curve of the surrounding rock relative to the embedding depth of the pile. (**a**) The upper blocking (U-b) type. (**b**) The lower supporting type. (**c**) The upper block lower support type.  
tunnel crown and the spandrel of the mountainside. The arch foot positions on both sides of the tunnel are prone to stress concentration phenomena. The displacement deformation in the tunnel is as follows: crown > right shoulder > left shoulder > arch bottom.
3. An optimized control scheme of anti-slide piles for controlling the stability of surrounding rock is proposed by analyzing four factors, namely, the forms of the anti-slide piles, the spacing of pile tunnels, the diameter of the piles, and the depth of piles embedded in the bedrock. The reinforcement effects of the three types are ranked from strongest to weakest as follows: the U-b and L-s > the upper blocking (U-b) > the lower supporting (L-s). The results indicate that the smaller the distance between the anti-slide pile and the tunnel, the stronger the reinforcement effect. When the length and diameter of the anti-slide pile are constant, the increased depth of the embedded sliding bed will steadily improve its deformation control effect.  
Conceptualization, Y.C. and P.L.; methodology, Y.C.; software, S.L.; validation, Z.S., P.L. and S.Z.; investigation, Z.S.; data curation, S.Z. and S.L.; writing--original draft preparation, Y.C. and S.L.; writing--review and editing, P.L.; visualization, Y.C.; supervision, P.L. All authors have read and agreed to the published version of the manuscript.  
This work is supported by the National Natural Science Foundation of China (nos. 52278383, 51978019, and 52004145) and the Natural Science Foundation of Beijing Municipality (no. 8222004). The financial support is greatly appreciated.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.