## 1 Introduction  
Kars is widely distributed around the world, and it causes great inconvenience to the achievement of engineering construction projects. Regions in the southwest of China, such as Yunnan and Guizhou, as well as other regions of China, are typified by steep hills and plenty of Karst terrain [1; 2; 3; 4]. With the continuous improvement of China's \"western development\" strategy, the prevalence of karst tunnel construction is increasing rapidly, and various technical problems of karst tunnels are constantly appearing [5; 6]. Passing through a large karst cave can be considered as one of the main difficulties in tunnel construction that will impose higher theoretical and technological requirements on karst cave treatment. The study aims to identify and analyze a powerful new method for the implementation of karst tunnels. In this regard, there are many relevant studies and engineering applications carried out by scholars that deal with large karst caves revealed during tunnel construction, the main aspects of which are exemplified as follows: [PERSON] et al. [7] treated a karst cave in a tunnel floor using the beam and plate method, and also used backfilling to treat the revealed karst cave. [PERSON] et al. [8] introduced the requirements of karst tunnel treatment, grouting materials, construction procedures, and effect detection. [PERSON] et al. [9] and [PERSON] et al. [10] studied the application of alkali-resistant fiberglass grouting material in karst cave treatment. [PERSON] et al. [11] found that the methods of pile foundation treatment at the bottom of the tunnel, strengthening the surrounding rock of the tunnel by full-section grouting, and supporting the top of the karst tunnel with an anchor net and shotcrete are effective. [PERSON] et al. [12] focused on the Naqiu tunnel hall karst cave project, and used the pile-bearing platform-retaining wall method to control the karst cave. [PERSON] et al. [13] designed a 58 m bridge through a large karst cave. [PERSON] et al. [14] proposed a new controlled grouting method and grouting material for the pre-reinforcement of the underwater karst area of a shield tunnel. [PERSON] et al. [15] showed that the treatment technology of an ultralarge karst cave in the Yawan tunnel, which is treated at the bottom of the tunnel by a continuous composite beam bridge, and the wall of the karst cave is treated by the combined support of an anchor net and spray. [PERSON] et al. [16] reported the treatment of large karst caves encountered during the construction of the Limushan tunnel by backfilling. [PERSON] et al. [17] treated a large karst cave in the Shangjiawan tunnel with plugging and crossing methods. [PERSON] [18] analyzed the advantages and disadvantages of longitudinal retaining walls, pile foundation-bearing platforms, and backfilling in tunneling through large karst caves from the perspectives of cost, safety, convenience, and time limitations. He [19] used a roundabout method to turn a revealed large cave into a side hidden cave. [PERSON] [20] and [PERSON] [21] analyzed the safety problems of limestone during mining. Based on the results of the above scholars, in view of the treatment technology of large karst caves revealed by tunnels, researchers have combined the practical projects and summarized the rich experience in treatment technology. In general, various technologies can be adopted to treat large karst caves. However, these existing technologies are lacking in commonality because they are based on specific engineering characteristics. There is a lack of a systematic method to guide the selection of one or more treatment technologies. To guarantee that the tunnels through large karst caves can achieve the purposes of convenience, high efficiency, safety, and systematicity, it is necessary to construct a complete set of technologies in order to achieve the comprehensive treatment of tunnels through large karst caves.