This study aims to establish a proper finite element modeling method to understand the stress behaviors of second lining concrete of a NATM tunnel at the crown and areas close to invert of the tunnel. A commercial FEM package named “ASTEA MACS” was utilized for the analysis incorporating nonlinear concrete material behaviour. The simulation results were compared with actual site measurements, where it was observed that appropriate modeling of the construction and structural joint conditions played a vital role in accurate simulation of the structural behaviour of the second lining concrete. It was also proved that appropriate modellings of thermal boundary conditions for heat transfer between the second lining and the environment, and of the thermal property of water proofing sheet between the second lining and the first lining were also indispensable for accurate simulation of early age temperature distribution of the second lining. Considering the stress distributions at two locations of the second lining in the thickness direction, it was observed that the crown cracks might be non-penetrating cracks and the cracks close to invert might be penetrating cracks.
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