LAUSR

Abstract The segmental tunnel linings with cracks affected by the mesostructured of concrete exhibits heterogeneous and nonlinear behaviors in the cracked area. However, there are obvious multiscale phenomena considering the mesoscopic features including aggregates, mortars, and interface transition zones and the non-damaged zones of the tunnel lining. If the cracks are not considered, then the mechanical behavior of the tunnel lining is misestimated. Therefore, a novel multiscale modeling method is proposed in which potentially damaged and non-damaged zones are recognized according to pre-analysis results and then simulated at different scales. In the model, mesoscopic features within the potentially damaged zones are modeled using a mesostructure cohesive zone method, while the other zones are simulated as a macroscopic homogeneous material. Herein, the mesostructure cohesive zone model has been used to incorporate the mesoscopic constituents and simulate the random propagation of multiple cracks. This is very useful for characterizing the features of multiple cracks and evaluating the mechanical behavior of the segmental tunnel lining. After the multiscale model has been validated using the experimental results, numerical simulations of the lining segment are carried out under different loading paths to investigate the evolution characteristics of multiple cracks and their impact on the tunnel lining performance. The study demonstrates that the proposed multiscale model is effective and accurate for modeling the random evolution of the multiple cracks and evaluating the load capacity of the segment under different loading paths. The stiffness of the lining was found to be not only dependent on the loading path, but also on the crack features, which are narrow and densely packed in compression dominated segments, but are wide and dispersed in bending dominated segments. A formula has also been developed to predict crack depth from the observed crack mouth opening displacement. The proposed novel multiscale method is a major step forward in modeling the capacity of cracked concrete tunnel linings.