Research on durability of underground lining structures using damage theory.

Damage and fracture theories have been widely applied to reinforced concrete structures. However, their application to the investigation of the durability of underground structures is still very limited. Damage or deterioration may occur in the lining structures of underground structures under external loads, groundwater seepage and corrosive agents, which may seriously affect the durability and reliability of the structures. This paper analyses and summarises the current application status of damage theories in the durability study of concrete structures in detail, and proposes the concept of deterioration function to consider the degree of structural damage. Then, the application of the Gurson meso-damage model in the durability study of underground structures is introduced and analysed in terms of theory, formulation and procedure. This paper develops a model for a typical underground lining structure to simulate its performance under in-situ stresses and environmental conditions. In the developed model, assumptions are introduced to account for the corrosion progression of the steel bars in the structure and damage mechanics theory is applied to determine the damage stresses in the lining structure. In this way, the service life of the lining structure can be predicted. The analysis method developed in this paper can be extended and applied to durability problems in other similar engineering structures.