界面过渡区对混凝土动态力学行为影响分析

Effect of the interfacial transition zone on the dynamic macroscopic mechanical behavior of concrete

混凝土宏观力学行为由其细观结构形式决定。考虑细观非均质性的影响,将混凝土看作由骨料、砂浆基质和界面过渡区组成的三相复合材料,其中骨料为弹性体,砂浆基质及界面过渡区的力学性能采用耦合材料应变率效应的塑性损伤本构模型来描述。为探讨界面过渡区对混凝土动态力学行为的影响,对不同加载速率下双边缺口混凝土试件的拉伸力学行为、混凝土梁弯拉破坏行为及混凝土试件单轴压缩力学行为进行了数值研究。数值结果表明:当加载速率较小时,界面过渡区的力学性能对混凝土动态破坏模式和宏观力学性能有显著的影响;而当加载速率(名义应变率>50/s,如冲击载荷)很大时,混凝土动态破坏模式基本不受界面过渡区力学性能的影响。

The global mechanical behavior of concrete is determined by its meso-/micro-scopic components. Con- crete is regarded as a three-phase composite composed of aggregate, mortar matrix and interracial transition zone （i. e. ITZ） herein. It is assumed that the aggregate is elastic, which would not be damaged, and the plasticity damaged model combined with the material strain-rate effect is employed to describe the mechanical properties of mortar matrix and the ITZ. To investigate the effect of the ITZ mechanical properties on the dynamic mechanical properties of concrete, a flexural-tensile sample of concrete beam, a double-edged notched concrete sample under uniaxial tension and a concrete sample subjected to uniaxial compression are employed. The numerical results indi- cate that the mechanical properties of the ITZ have an obvious influence on the failure mode and mechanical proper- ties of concrete subjected to a lower loading rate. However, when the loading rate is very high （ such as impact load whose nominal strain rate is larger than 50/s） , the corresponding dynamic failure modes and the macroscopic me- chanical properties of concrete are almost not affected by the mechanical properties of ITZ.