Effect of high temperatures on the behavior of concrete tunnel linings: a numerical study

In this work, the performance of concrete tunnel linings subjected to high temperatures is assessed by performing 3D FE simula-tions. The analyses account for all the different stages of lining construction and use, from its installation, to its service life, to the possible spreading of fire. In order to realistically represent the soil excavation phase and the subsequent lining installation, a step-by-step procedure is followed, whereas a sequentially coupled thermo-mechanical procedure is applied for the fire stage. The behavior of concrete subjected to high temperatures is described by using the non-linear constitutive model “2D-PARC FIRE”. This model considers all the main features governing concrete behavior (i.e. cracking, crushing, shrinkage, creep and time-dependency of concrete mechanical properties) by also including the effects of thermal strains and the degradation of material properties due to fire.