Analysis on deformation and structural safety of a novel concrete-filled steel tube support system in loess tunnel

Because the conventional support system has its own limitations, it is hard to stabilize the surrounding soil which frequently causes the tunnel damage in loess area. Therefore, there has been aroused a great concern for controlling the large deformation during loess tunnel construction. Based on a successful application of the concrete-filled steel tube (CFST) in mining engineering, a novel support type of CFST support system is proposed in this article. The new support system highlights to strengthen the primary lining and to improve the stress distribution between primary and secondary lining. The convergence confinement method and finite element analysis were adopted to investigate the performance of CFST support system and conventional support system, respectively. The results showed that CFST support system presented a better support performance with higher stiffness and greater bearing capacity compared with the conventional support system. In addition, CFST support system effectively decreased the tunnel deformation and extensively increased the safety reserve of secondary lining during the tunneling process. Also, a parametric study was conducted and included investigations on the inner concrete strength, the thickness of the steel tube and the diameter of the CFST. These results help to improve the loess tunnel design and construction.

Automated summary

The article introduces a novel CFST support system which enhances the support performance and bearing capacity by strengthening the primary lining and improving stress distribution. Through parameter studies, the design and construction of loess tunnels can be further improved.