Geometric deviations are inevitably generated during tunnel lining construction. These deviations result from construction inaccuracies. They pose potential risks to long-term structural safety and engineering quality. Traditional numerical simulations are based on idealized design cross-sections. This approach is limited in reflecting actual mechanical behavior. In this study, a refined modeling and safety assessment method is developed. Construction-induced geometric deviations are incorporated into the analysis. Optimized geometric fitting and mesh reconstruction algorithms are employed. Large-scale irregular point cloud data are efficiently processed. A full-scale solid finite element model is constructed. Actual construction deviations are represented in this model. The results are systematically compared with those from the conventional design model. It is revealed that construction-induced geometric deviations alter internal force transmission paths. Asymmetric deformation is induced. Localized stress concentrations are observed. The ideal stress state is predicted by the design model. In contrast, stiffness degradation is observed in the as-built model. This degradation is significant in vulnerable regions such as the haunch on the heavily loaded side. A considerable reduction in the local safety factor is also observed. The overestimation of safety redundancy is quantified when geometric variations are neglected. The results indicate that incorporating field-measured point cloud data into structural simulations can improve the geometric realism of tunnel-lining assessment and assist in identifying potential high-risk zones.
Yang et al. (Tue,) studied this question.