Prediction of tunnels support system loads using analytical and numerical methods

Design of support system is One of the most important issues in tunnels design. Therefore, in order to safe design of support system, determination of internal loads has a special importance. In this paper, analytical and numerical methods were used to determine of internal loads, and in 2D and 3D states, the results of these methods were compared with the assumption of no slip and full slip conditions. Findings prove that in different sections of support system, the axial force obtained from full slip condition is more uniform than that of no slip condition, and the bending moment of full slip condition is higher than that of no slip condition. According to results, an increase in stiffness contrast between support system and ground results in an increase in the internal loads. Moreover, by increasing of the tunnel radius, the bending moment decreases and axial force increases.