界面过渡区力学特性对水工混凝土断裂性能的影响

Effect of Mechanical Properties of Interfacial Transition Zone on Fracture Properties of Hydraulic Concrete

混凝土界面过渡区(interfacial transition zone,ITZ)是影响混凝土宏观断裂性能的最薄弱细观组分,但现阶段对于其力学特性的测定仍极为困难,致使在混凝土细观力学分析中通常采用人为假定的方式确定其力学参数.鉴于此,本文建立了水工全级配混凝土细观有限元计算模型,并开展了一系列不同ITZ力学参数下的拉伸断裂细观数值模拟,系统研究了ITZ主要力学参数取值对水工混凝土断裂性能的影响规律.研究表明,ITZ弹性模量的变化对混凝土断裂性能影响很小;随着ITZ抗拉强度的降低,混凝土的抗拉强度减小,峰值应变增加,弹性模量变化很小,断裂模式也会发生变化,并导致断裂能的改变;ITZ断裂能的变化主要影响混凝土断裂能.研究成果可为水工混凝土细观力学分析中ITZ力学参数的合理确定提供参考.

The interfacial transition zone(ITZ)is the weakest mesoscopic component that affects the macroscopic fracture properties of concrete.However,the determination of its mechanical properties is so difficult that its properties are usually assumed in micromechanical analysis of concrete.In view of this,this paper establishes a mesoscopic finite element calculation model for hydraulic full-grade concrete,and carries out a series of numerical simulations of meso-structural tensile fracture under different ITZ mechanical parameters to systematically study the influence of the main mechanical characteristics of ITZ on hydraulic concrete fracture property.The results show that the ITZ elastic modulus has little effect on the fracture properties of concrete.As the decreases of ITZ tensile strength,the tensile strength of concrete decreases and the peak strain increase;and the fracture energy altered with changes in fracture mode;and the elastic modulus is almost constant.The ITZ fracture energy mainly affects concrete fracture energy.The research results can provide reference for the reasonable determination of the ITZ mechanical parameters in the mesomechanical analysis of hydraulic concrete.