Research On Chloride Ion Diffusion And Their Influential Factors In Transmission Line Reinforced Concrete Structures

The corrosion of steel rebar, which is induced by chloride ion(Cl–) penetration, was the main cause to the reinforced concrete foundation failure for the transmission line tower in chloride environments. The diffusivity of chloride ion can be aggravated by stress damage and the cracks due to the interactions between all kinds of load levels and the external factors, which will obviously reduce the service life of reinforced concrete structures. In this thesis, chloride ion diffusion mechanisms and influential factors in transmission line reinforced concrete foundation have been investigated by using the multiphysics coupling methods. The main research contents include:According to the practical features of transmission line engineering and considering the coupling effect of all loads and environment factors, one-dimension(1D) and two-dimension(2D) chloride ion diffusion models in stress-induced concretes are established. In addition, starting from the energy law, chemo-mechanical coupling theoretical diffusion model is also given.(Chapter 2)Base on the diffusive models in Chapter 2, the effects of environment factors, concrete structural factors(such as, cross-section shape, size and cover thickness, etc) and steel rebar on the chloride ion diffusivity in transmission line foundation has been numerically studied. The internal relationship between chloride diffusive rules and all kinds of influential factors is obtained.(Chapter 3)Cracked reinforced concrete foundation in high-voltage transmission line is selected as the research object. Combined with modified dual porosity medium model and the improved Fick Second Law, the influences of crack width, crack depth and crack distribution location on the chloride ion diffusivity in reinforced concretes are analyzed in detail. The relationship between crack distribution inhomogeneous and chloride ion diffusivity is also established. In the meanwhile, based on the chemo-mechanics diffusion model, the effects of crack defect on the chloride diffusive property in reinforced concretes subject to tensile and compressive loadings are also discussed.(Chapter 4)...