硫酸盐侵蚀下混凝土损伤演化的新模型

A New Model of Damage Evolution in Concrete under Sulfate Attack

根据混凝土的拉伸强度给出了微裂纹的起裂条件,再由微裂纹成核率的"白模型"得到了损伤驱动应力相关的微裂纹成核率方程.在假定微裂纹的长大服从Seaman扩展方程的基础上,结合微裂纹数密度演化的平衡方程,得到了特征线上微裂纹数密度演化的一阶常微分方程;通过对微裂纹的体积积分,得到了混凝土损伤劣化的新模型,模型的相关参数则由实验确定.研究结果表明:得到的损伤劣化模型可以较好地反映混凝土侵蚀损伤演化规律.

Based on the tensile strength of the concrete, we provide a criterion for the micro-crack＇s nucleation, We also derive the equation of micro-crack nucleation rate on the basis of Bai＇s model,, which relates to the driving force of damage. Assuming that the micro-crack growth obeys Seaman extended equation, and combining with the equilibrium equation of the evolution of the micro-crack number density, we set uo the first-order ordinary differential equation of the micro-crack number density evolution for the characteristic curve. Per the volume integral of the micro-crack, the new model of the degradation of concrete damage has been built. The parameters of this model are determined by the experimental results. The results show that the damage degradation model obtained in this research can better reflect the evolution rule of concrete erosion damage.