# Landslide-Tunnel Interactions and Control Countermeasures under an Orthogonal System
## 1 Introduction
[PERSON] and [PERSON] (2018) conducted in-depth analyses and research on the mechanisms of tunnel deformation caused by interactions in tunnel-landslide systems, using the numerical analysis method to calculate landslide deformation, stress, and tunnel deformation in detail. Their results showed that a final treatment scheme based on stress and deformation control theory can be used as a reference for similar future projects [16]. [PERSON] et al. (2012) divided tunnel-landslide systems into three major types based on their spatial relationships: parallel, orthogonal, and oblique intersections; they studied the stress patterns for each type. By analyzing this interaction, the tunnel's failure mode and stress can be well understood, providing a good reference value for controlling tunnel and landslide stability [17]. Similarly, [PERSON] et al. (2014) considered the relative position of the tunnel and the landslide, analyzing an unstable landslide with repeated failures in the tunnel lining. They determined the main factors affecting the failure and deformation of the landslide and tunnel [18]. The relative positional relationship between a tunnel and a sliding surface determines the interaction mode and deformation characteristics. [PERSON] et al. (2021) proposed a simplified analytical method to evaluate deformation caused by landslides in existing tunnels and then used the transfer coefficient method and the limit equilibrium method to calculate the landslide pressure. They then compared their three-dimensional numerical simulation results with a simplified analytical solution, and good consistency was achieved [19]. [PERSON] et al. (2021) studied the causes, stress modes, and deformation characteristics of landslide collapse, looking at the interaction between tunnel landslides under an orthogonal tunnel and sliding surface system. The results showed that the tunnel-landslide system's interaction decreases with increased distance between the two [20]. [PERSON] et al. (2015) analyzed an unstable landslide, showing that tunnel excavation can lead to landslide instability. Excavation affects the displacement velocity of a landslide and the damage to the tunnel's lining structure. The interaction between a tunnel and an unstable landslide is related to the tunnel's diameter and the distance between the tunnel and the sliding surface [21]. [PERSON] et al. (2016) and [PERSON] et al. (2015) carried out long-term landslide monitoring, and they established a law of interaction in tunnel and landslide systems. Landslides after tunnel construction reduce the opera tional safety of tunnels [22; 23]. [PERSON] et al. (2013) conducted a risk assessment of a tunnel crossing a landslide and analyzed the interaction between the tunnel's structure and the local landslide's instability [24]. This interaction can be studied through geomorphological investigations, geological explorations, monitoring activities, and numerical simulation. The above studies show that this interaction determines the structural stability of tunnels and landslides. Based on different positional relationships between landslides and tunnels, this study analyzes their interactions for three different positions. Through theoretical analysis, a mechanical calculation model for tunnels and landslides is established. At an engineering site, using a tunnel crossing a landslide surface as an example, a numerical simulation is established to reveal the stress characteristics and displacement variation law of the tunnel; moreover, the effect of anti-slide pile reinforcement measures on its stability is discussed. By studying the stress characteristics and deformation laws of tunnels under the influence of landslides, we can provide a reference for ways to control the stability of rock surrounding tunnels and landslides.