Progressive failure process of secondary lining of a tunnel under creep effect of surrounding rock

• Published in: Tunnelling and underground space technology 2019-08, Vol.90, p.76-98
• Main Authors: Xu, Guowen, He, Chuan, Yang, Qinhao, Wang, Bo
• Format: Article
• Language: English
• Subjects: Computer simulation; Cracking (fracturing); Cracks; Creep; Damage; Deformation mechanisms; Discrete element method; Elastic limit; Failure; Field investigations; Fracture mechanics; Lateral pressure; Lateral stability; Mathematical models; Microcracks; Model testing; Mountain tunnels; Progressive failure; Rock deformation; Secondary lining; Similarity; Time dependence; Tunnels
• ISSN: 0886-7798; 1878-4364
• DOI: 10.1016/j.tust.2019.04.024

During the operation of tunnels, a problem that is encountered often is the cracking of secondary lining caused by the time-dependent deformation of weak surrounding rocks. In this article, the Dujia mountain tunnel, which is situated in a weak and crushing phyllite stratum, was taken as an example to study this issue. First, we conducted a field investigation of the cracking situation of the secondary lining. Then, the similarity model test and particle-discrete-element numerical approach were used to study the failure process of the secondary lining. The results showed that the similarity model test and the results of numerical simulation were consistent with respect to the order in which cracks occurred and the final failure pattern. The progressive failure process can be divided into four stages, i.e., (1) the elastic stage, (2) the initial damage stage, (3) the ultimate limit stage, and (4) the instability stage. For a lateral pressure coefficient (λ) > 1, cracks initially appeared at the left haunch, the right haunch, and the spandrel due to bending damage caused by large-eccentricity compression. For λ = 1, cracks appeared first at the left arch springing because of the compressive and shear damage. For λ