Time-variant probabilistic random degradation model on flexural capacity of road tunnel linings
Xingbo Han, Xingbo Han, Kang Gao, Fei Ye, Xin Han, Xin Han
Abstract
A time-variant random degradation model for assessing the flexural capacity of tunnel lining is proposed. By using the double reinforced beam model, the governing equation of moment capacity for tunnel lining is established with the consideration of the reduction of the steel area and the concrete-steel bond strength. Moreover, both carbonation penetration and chloride corrosion of lining are incorporated in this model. Then the theoretical formulations are used to obtain the probabilistic time-dependent flexural capacity responses of tunnel lining. To further optimise the target model, the global sensitivity analysis approach is employed to search the critical parameters. Additionally, applicability, accuracy, and efficiency of the proposed approach are rigorously investigated by comparing the probabilistic information of the capacity degradation model with that of Monte-Carlo simulation method from practically motivated examples. Finally, time-variant probabilistic features of lining flexural capacity are systematically studied, and the numerical results showed that the tension bars are hard to reach its yield strength when considering the deformation incompatibility caused by rust formation. The moment capacity follows the normal distribution for both normal and lognormal distributed lining thickness during all its life cycle.