考虑过渡区界面影响的混凝土宏观力学性质研究

RESEARCH ON THE INFLUENCE OF INTERFACIAL TRANSITION ZONE ON THE MACRO-MECHANICAL PROPERTIES OF CONCRETE

混凝土材料的宏观力学特性及破坏机理由其细观组分来决定,界面过渡区是影响混凝土断裂破坏路径及宏观力学特性的重要因素。认为界面过渡区是区别于远处砂浆基质的一层含较高孔隙率的近场砂浆材料,采用"两步等效法"得到了混凝土细观单元的等效本构关系模型。最后基于细观单元等效化方法分析了在单轴拉伸、单轴压缩及弯拉载荷条件下混凝土试件的破坏过程及宏观力学性质,探讨了界面过渡区对混凝土力学特性的影响,并与随机骨料模型分析结果进行了对比。结果表明:界面相的存在对混凝土的弹性模量、强度及残余强度等力学性质有很大影响,在对混凝土宏观力学特性及细观断裂破坏过程进行研究时不可忽略其影响。

Macroscopic mechanical properties and failure mechanism of concrete are determined by the microscopic components. And the interface between aggregate and cement mortar is an important factor that affects the failure path and macro-mechanical properties of concrete. The interfacial transition zone is regarded as a layer of near-field mortar with a high porosity different from the far-field mortar matrix. The mechanical properties of the three-phase composite meso elements of concrete are deduced by a ＂two-step equivalent method＂, and then the equivalent constitutive relationship of each meso element is obtained. Based on the meso element equivalent model, the damage process and the macro-mechanical properties of two-grade concrete are investigated under the loading conditions of uniaxial tension, uniaxial compression and bending. And the influence of interface-phase on the mechanical properties of concrete is discussed. Besides, the results of the present model are compared with the ones by a random aggregate model. The analysis results show that the existence of interfacial transition zone has a great influence on the macro elastic modulus, strength and residual strength of concrete, which should not be neglected when analyzing on the macro-mechanical properties and damage fracture of concrete.