三级配混凝土单轴破坏的细观数值模拟

Meso-structure numerical simulation of uniaxial failure of three-graded concrete

将混凝土看成是由骨料、界面和砂浆组成的非均质复合材料,采用非线性有限元软件Marc对东江拱坝三级配混凝土试件单轴受拉、单轴受压破坏的全过程进行数值模拟.按照试件的实际配比计算出各种粒径骨料的数目,采用蒙特卡罗法对混凝土骨料进行随机投放,生成试件的随机骨料模型.研究中,单轴受拉时采用最大拉应力准则,并考虑了材料的软化;单轴受压时采用线性莫尔库伦准则.结果表明,混凝土的力学性能与其内部的细观结构组成密切相关,材料的宏观破坏是细观结构破坏累积的结果,无论是受拉时的开裂还是受压时的屈服,几乎都首先发生在界面上.

Concrete was taken as inhomogeneous composites consisting of mortar, aggregate and their interface. Numerical simulation was carried out by use of nonlinear finite element software Marc, which could simulate the whole failure process of specimens of three-graded concrete subjected to uniaxial compression and tension for the Dongjiang arch dam. The Monte Carlo method was used to generate the random aggregate model, and the number of aggregate of different sizes was determined according to the actual mix proportion. The maximum tensile stress criterion and the linear Mohr-Coulomb criterion were adopted in the study of specimens subjected to uniaxial tension and uniaxial compression, respectively, with the softening of materials taken into account. The results indicate that the mechanical performance of concrete is closely related to its meso-structure, and the meso-failure is the result of accumulation of damages to its meso-structure. The results also show that the interface is the weakest part, where tension-induced cracks or compression-induced yield are most likely to occur.