## 1 Introduction  
In recent years, the construction of highways and railroads has gradually developed to the southwest and northwest, facing difficulties such as multiple high mountains and extremely complex engineering and geological conditions. According to engineering regulations, tunnel construction should avoid crossing landslides as far as possible but, in reality, the occurrence of landslides has a special, spatial, and temporal complexity, and large-scale ancient landslides are even more difficult to find during preliminary investigations and planning. Therefore, tunnel construction inevitably crosses landslides, and landslides resurrect during tunnel operation and cause tunnel damage, affecting the normal operation of the tunnel. There have been many domestic and international research results on single aspects of landslides or tunnels, but there are fewer studies that incorporate the overall interaction of tunnel landslides. Foreign Japanese scholars [PERSON] and [PERSON] [1] in \"Landslides and slope failures and their prevention and control\", due to the disturbances that occur during tunnel construction slope sliding, employ a \"tunnel-landslide system\" for a systematic analysis, creating a preliminary summary of the tunnel-landslide system under the conditions of the formation of landslide damage phenomena and their causes. [PERSON] et al. [2] analyzed the mutual influence of the tunnel-landslide system in the case of ancient rock body landslides and landslides caused by heavy rainfall due to tunnel excavation and explained the interrelationships between ancient rock body landslides and tunnel excavation disturbances. Domestic scholars, such as [PERSON], [PERSON], [PERSON], and [PERSON] [3; 4; 5; 6], through engineering, practical experience, and theoretical research, summarized a geological model of the common system of tunnel-landslide combinations, analyzed the mechanical mechanism of deformation of the tunnel-landslide system as a whole, and put forward the corresponding prevention and reinforcement measures of the tunnel-landslide system, according to different models. However, little research has been carried out on the stability monitoring of the tunnel-landslide system as a whole. In 2016, [PERSON] proposed [PERSON]'s law of variation in forces for catastrophic changes in geologic bodies [7], constructed a mechanics model of two-body landslide catastrophes based on the measurement of Newtonian force change, explained the mechanics mode of the slope from deformation to destruction, and believed that landslide early warnings could be achieved by monitoring the change of the force on the sliding surface at the time of the occurrence of the landslide. Subsequently, [PERSON] independently developed the Newtonian force remote monitoring and early warning system, as well as the NPR constant-resistance large deformation anchor cable for the Newtonian force monitoring of landslides [8]. The Newtonian force landslide early warning model is proposed to be capable of \"monitoring curve sudden rise or fall characterizes the surface cracks, large jumps characterize large cracks, small jumps characterize small cracks [9]\". The model has been successfully used for early warning in 16 landslide disaster monitoring instances. Based on the Newtonian force monitoring and warning system, [PERSON] and [PERSON] have successfully issued early warnings of near-slips through several practical applications in engineering sites and, meanwhile, proved the scientific nature of the theory and practical feasibility through numerical simulation and mechanical analysis [10; 11]. At present, there is still a lack of research on the monitoring and early warning of tunnel-crossing landslides, such a complex system of geologic hazards [12; 13], and some advanced monitoring techniques can still not be linked to landslide-induced tunnel deformation and damage processes.