骨料级配对二维模型混凝土单轴抗拉强度影响的理论研究

混凝土尺寸效应及其宏观力学非线性根源于其材料细观组成的非均质性。结合混凝土细观结构形式，将混凝土看作由骨料颗粒、砂浆基质及界面过渡区组成的复合材料。采用双线性弹性损伤模型来描述砂浆基质及界面过渡区的力学行为，假定骨料颗粒为弹性体而不发生破坏，进而推导并获得了单轴拉伸条件下不同骨料颗粒级配混凝土断裂裂缝扩展路径长度及其抗拉强度的理论解。最后，对比了建立的理论公式结果与细观尺度数值模拟结果，验证了构建的关于裂缝长度及抗拉强度理论解的准确性和合理性。

A THEORETICAL STUDY ON THE INFLUENCE OF AGGREGATE GRADATION ON THE TENSILE STRENGTH OF 2-DIMENSIONAL MODEL CONCRETE

The size effect and macroscopic mechanical nonlinearity of concrete are caused by its inherent heterogeneity. Considering the mesoscopic structure, concrete is treated as a composite material consisting of aggregate, mortar matrix and an interfacial transition zone (ITZ). The double-line elastic-damage model has been borrowed to describe the mechanical properties of the mortar matrix and the ITZs. Aggregate is assumed to be elastic, so it cannot be damaged. Then, a general expression of the length of the fracture crack propagation path and a theoretical solution for the uniaxial tensile strength for different graded concretes are established. Finally, the theoretical resolution is compared with the simulation results at meso-scale and the rationality of the theoretical formulae for crack length and tensile strength from the present work is thereby validated.