Study on the damage evolution in secondary tunnel lining under the combined actions of corrosion degradation of preliminary support and creep deformation of surrounding rock

Abstract

This paper presents a numerical approach to study the damage evolution of secondary tunnel lining under the combined actions of corrosion of the preliminary support and the creep deformation of the surrounding rock. This improved numerical approach contains three main models for: (1) tensile failure of corroding rock bolt; (2) yielding of corroding supporting steel arch; and (3) elastoplastic damage of secondary tunnel lining. The corroded rock bolt's failure criterion under tension, the yield criterion of a corroded steel arch under combined compression and bending actions were developed and programmed using FLAC3D's FISH language programming. For the secondary lining failure, a Mohr-Coulomb criterion with a damage formulation based on a statistical damage distribution model was adopted. The validity of the models was verified, and the mechanical response of the supporting structures was investigated. The results showed that: (1) a combined strength envelop can reasonably simulate the mechanical behavior of the steel arch under pure compression, pure bending, and compression-bending action; (2) the corrosion fracture criterion of the rock bolt can adequately reflect rock bolt axial force development process of nonlinear increase and decrease, and failure with the increase of axial strain; (3) damage of concrete can be adequately described by the damage constitutive model, with the damage parameters exerting a strong influence on the post-peak behavior of concrete; and (4) the damage level of the plastic zone at the same location in secondary lining for the corrosion yield model is larger than that predicted from the original FLAC3D structural models.