A microcrack-based anisotropic damage model for concrete under mechanical loading and calcium leaching

Abstract

In underground construction, concrete is always subjected to triaxial stress and calcium ion leaching, which results in anisotropic damage to concrete and reduce the durability of the structure. To capture the anisotropic damage properties of concrete subjected to mechanical-chemical coupling effects and predict the durability of underground concrete structure accurately, a microcrack-based anisotropic damage model is proposed. The mechanical damage, reflecting the density and direction of the microcracks caused by mechanical loading, is defined by a second-order tensor. The degree of chemical damage is defined by the amount of solid calcium phase lost in the concrete. Considering oriented microcrack and the influence of chemical damage on fracture toughness, the anisotropic mechanical damage evolution law of microcrack was established by linear fracture mechanics. A phenomenological chemical model governed by a diffusion law considering the variation of diffusion coefficient with stress induced microcracks is defined to describe the calcium dissolution process. The simulation results are in good agreement with the experimental results. Compared with the traditional elastoplastic damage model, the maximum creep error is only 0.114 ‰.