Tunnel stress path during excavation was investigated in the study scope. The triple-center section is commonly designated for highway tunnels, but the analytical solution of the stress state for a non-circular tunnel section with multiple bench excavations is difficult to obtain. Our investigation provides an algorithmic procedure which reliably evaluates stress adjustment of a bench excavation with respect to the three-dimensional state of stress. Evaluation of a safety factor at the tunnel face during advancement is performed following the stress path and principal stress space.
