基于数值方法的混凝土细观结构变化规律与力学性能研究

本文基于分形理论,以混凝土试件细观结构中的骨料面积-界面周长关系作为细观结构的表征指标,通过分形维方法将其量化,利用数值方法研究了混凝土试件的细观结构变化规律,分析了试件细观结构变化对其力学性能的影响,并在此基础上进一步探讨了细观结构变化对试件力学特性的影响机理。研究发现:(1)试件骨料投放率的变化对细观结构影响甚小,而试件尺寸的变化则对其影响较大;(2)试件尺寸变化对试件承载力学性能的影响更大,而骨料投放率变化对其影响则较小:骨料投放的增多对承载力的提升作用和对整体应力水平的降低作用在大尺寸试件中更为明显;(3)骨料投放率的增大能提升试件局部开裂应力,但会降低开裂应变,增大开裂脆性,试件破坏呈现出明显的局部特性。

Research on concrete mesoscopic structure changing law and mechanical property based on numerical methods

Taking specimen aggregate area and interface perimeter relation as the index for representing con- crete mesostructure, specimen mesostructure changing law is studied with numerical method by quantifying the index with fractal methods. Then the effect of mesostructure changing on specimen mechanical property and the mechanism are also further studied. Through the research, following results are obtained:(1) the change of aggregate volume fraction affects the mesostructure little, while the change of specimen size has a lot of influence on the mesostructure;(2) the change of specimen size affects its mechanical property a lot,while the change of aggregate volume fraction barely affects it:that is the contribution of aggregate vol- ume fraction increase on specimen bearing capacity increase and global stress level decrease would be more obviously with larger size;(3) the increase of aggregate volume fraction would not only increase local cracking stress, but also decrease the cracking strain, resulting in larger cracking brittleness, thus the cracking localization feature would be more obviously in larger aggregate volume fraction situation.