Elasto-Plastic Solution for a Circular Lined Tunnel Considering Yield Criteria for Surrounding Rock and Functionally Graded Lining in Cold-Region Tunnels

Tunnel construction plays an important role in the sustainable development of the socio-economic framework of the country. With the rapid development of the economy and the expansion of the transportation network in western China, numerous tunnels will inevitably be constructed in cold regions in the future. In order to analyze the mechanical properties of lined tunnels in cold regions from a new theoretical perspective, an elasto-plastic mechanical model of a circular lined tunnel is proposed, considering several yield criteria for the surrounding rock and the functionally graded feature of the lining. The proposed model is compared with an existing model and test results obtained by other researchers, and a satisfactory agreement is obtained. The influence of the main model parameters on the plastic zone, the radial pressure acting on the outer surface of the lining, and the stress and displacement fields is further explored. The circumferential stresses in the lining zone calculated using the DP3 criterion are the largest, and the ones with the MO criterion are the smallest. The influence of the yield criterion on the displacement fields in the frozen zone decreases with the increase in the distance from the tunnel. The circumferential stresses and radial displacements in the lining zone and frozen zone increase with the increase in the radial pressure acting on the inner surface of the lining. The research results can provide useful insight into the design and construction of tunnels in cold regions.