Resistance to Sulfate Attack and Chemo-Damage-Transport Model of Sulfate Ions for Tunnel Lining Concrete under the Action of Loading and Flowing Groundwater

In this study, resistance to sulfate attack and a chemo-damage-transport model of sulfate ions for tunnel lining concrete under the action of loading and flowing groundwater are investigated. The results show that in the initial stage of erosion, the relative dynamic elastic modulus of tunnel lining concrete and the sulfate ion concentration increase gradually. However, in the subsequent stage of erosion, the relative dynamic elastic modulus of tunnel lining concrete decreases gradually, and the increase in sulfate ion concentration accelerates. The defects of the tunnel lining concrete in the tensile zone and compressive zone can be expanded and closed, respectively, under the action of the loading. Meanwhile, the tunnel lining concrete can be corroded under the action of flowing groundwater. Therefore, the sulfate ion concentration in the tensile zone is the highest under the action of loading and flowing groundwater. The second highest value is obtained under the action of only flowing groundwater, which is followed by the action of static groundwater. The sulfate ion concentration in the pressure zone is the lowest under the action of loading and flowing groundwater. The chemical reaction in the process of sulfate erosion, damage of tunnel lining concrete by crystallization pressure and loading, and influence of flowing groundwater dissolution on calcium leaching are considered in combination, and a weight coefficient is introduced to characterize the influence of pore structure on the crystallization pressure. Finally, a chemo-damage-transport model of sulfate ions is established and its rationality is verified.