基于断裂力学的钢筋混凝土保护层锈胀开裂模型

本文基于钢筋均匀锈蚀时混凝土的开裂试验现象建立了混凝土保护层开裂的计算模型,考虑了混凝土和钢筋的实际变形情况以及混凝土界面中的原始裂纹与缺陷,裂纹在钢筋锈蚀膨胀作用下的起裂、扩展情况,利用断裂力学和弹性力学得到了混凝土保护层开裂时钢筋的膨胀力和均匀锈蚀率的理论预测模型.分析了影响钢筋锈胀开裂的诸多因素,认为混凝土保护层厚度的增加、混凝土材料界面相的加强、混凝土断裂韧度的提高和钢筋直径的变小都有利于钢筋混凝土结构耐久性的提升.理论模型计算结果与试验数据的对比表明,本文模型可用于混凝土亮中钢筋锈蚀胀裂的预测.

Fracture model for protective layer cracking of reinforced concrete structure due to rebar corrosion

The model for calculating the cracking of protective layer in reinforced concrete structure due to rebar corrosion was established according to the cracking phenomenon observed in experiment. In the model the real deformation of concrete and rebar as well as the initial cracking and defects of concrete were considered. On this basis, the initiation and development process of cracking due to expansion force of corrosion were predicted by a model established base on fracture mechanics and mechanics of elasticity. The factors affecting the cracking were analyzed. It is found that the increase of protective layer thickness, improvement of concrete strength, enhancement of concrete toughness and decrease of rebar diameter are in favor of elevating the durability of reinforced concrete structure. The comparison of calculation result with experimental data demonstrates that the proposed model is feasible for predicting the expansion cracking of concrete protective layer due to corrosion of rebar.