基于微观结构特征的混凝土动态抗拉强度提高机理及其统一模型

Unified model and mechanism for dynamic tensile strength increase of concrete base on its microstructure characteristics

通过总结和分析混凝土材料静动态强度及其微观结构特征的主要研究成果,从微观角度研究了混凝土动态抗拉强度提高机理。研究表明,基于微观结构特征研究混凝土动态抗拉强度提高机理是可行的,并建立了能够解释水灰比、养护条件、龄期、含水量以及不同加载速率等因素影响混凝土动态抗拉强度微观结构机理的统一模型。模型使混凝土动态抗拉强度形成得到了统一,即由固体材料效应、自由水效应以及惯性效应三部分组成,各部分在不同应变率阶段影响程度不同。

By means of summary and analysis on the main results of existing researches on static and dynamic tensile strength of concrete and its microstructure characteristics,the dynamic tensile strength mechanism of concrete was studied from the microscopic view point.The results show that it is feasible to investigate the dynamic tensile strength mechanism of concrete based on microstructure characteristics.A unified microstructure mechanism model is established.The model can explain many factors influencing the static and dynamic tensile strength,such as water cement ratio,curing conditions,concrete age,moisture content and different loading rates.The composition of the dynamic tensile strength of concrete is unified in the model.It composed of three parts,namely the solid material effect（dry strength and rate effect）,the free water effect（the capillary attraction of free water and Stefan effect）,and the inertial effect.At different strain rate stages,the degrees of influences of these three parts are different.