## 1 Introduction
The radial flexible members are those placed between the steel frame and the surrounding rock, and the circumferential flexible members are those embedded between the steel frames. Their principle is the same: all of them are to make the support have a large deformable capacity and sustained bearing capacity so that it can maximize the absorption or dissipation of energy in the surrounding rock during the working process. In summary, from the earliest mines used in the swan body to the slidable steel frame, let pressure anchor, energy-absorbing anchors, etc., and then used in tunnels behind the support can be compressed to fill the layer, flexible support, let pressure support and other types of support. As early as 1923, [PERSON] and [PERSON] [11] envisioned a support scheme in which a layer of round logs is filled between the U-frame and the surrounding rock or arranged in a circular pattern within the poured concrete lining, taking advantage of the low stiffness of the logs to allow for shrinkage to solve the problem of large deformations in the tunnel. [PERSON] [12] proposed that in the context of expansive surrounding rock tunnels, compressible foundations should be constructed in the lining invert, following which a compressible filling layer should be set behind the arch. Aiming at the problem of cracking the soft rock tunnel lining, [PERSON] and [PERSON] [13] proposed a support scheme involving setting a flexible layer between the primary support and the secondary lining, but the deformation tolerance of this support model proved low. Meanwhile, [PERSON] et al. [14] developed a constant resistance large deformation bolt capable of achieving up to a meter degree of deformation under a supporting force of 120-150 kN. Although this technology was found to be suitable for supporting both rock bursts and large-scale deformation, the processing costs and construction difficulties proved high. [PERSON] and [PERSON] [15] from Germany invented the Meypo pressure controller for tunnel ring setting and applied it to the Ibbenburen coal mine in Germany. Although it achieved the expected results, it was difficult to popularize due to its high processing costs and construction difficulties. Experimental studies by [PERSON] et al. [16] showed that the stress distribution in the lining support is more uniform when radial tubular dampers are compactly arranged compared to the spaced arrangement. Based on the concept of combining rigidity and softness, [PERSON] et al. [17; 18; 19] developed a \"rigid softness\" type of support by adding ring direction-controllable compression members to the supporting structure, which effectively solved the problem of large-scale tunnel deformation. It is ideal for ensuring the long-term stability of tunnels, especially when there is no space for buffer deformation after the completion of the secondary lining [20]. In general, many scholars have carried out a lot of fruitful research on the support forms of large deformation tunnels with soft rock, but many new support forms have low applicability, low economy, and long duration. Currently, the main types of tunnel sections are circular, arched, and rectangular, with arched tunnels being the most common. The study of structural forces in tunnels is primarily conducted via theoretical analysis, finite element calculations, and on-site monitoring. In this paper, we investigate the large deformation of arched tunnels using finite element calculations and on-site monitoring. This study aims to break the traditional design concept of large deformation support for soft rock tunnels and to propose an efficient, safe, and low-cost measure to solve the problem of large deformation in tunnels.