Abstract: It is important to understand the characteristics of the internal force distribution of the supporting struc? ture of a tunnel with multi-centered circular arch in complicated construction conditions to ensure safe tunnel construction. Based on the initial parameter method and site-measured pressures of the surrounding rock, an inversion expression for the internal force calculation of the supporting structure of the multi-centered circular arch tunnel is theoretically derived using the theory of a curved beam on an elastic foundation. Based on the measured pressures of the surrounding rock of a certain section of the Qixiaying tunnel, a back analysis is conducted for the internal force distribution of the tunnel lining structure and a safety evaluation of the weak parts of the tunnel structure is undertaken. The results show that site monitoring should be strengthened for the weak parts during construction since the bending moment and shearing force of the lining structure at the BG arc section are relatively large; monitoring and observation should also be improved since concrete cracking could occur at the tunnel crown due to bending.