基于细观层次的混凝土断裂过程及破坏机理的数值分析

笔者利用蒙特卡罗方法随机生成混凝土的骨料分布,以模拟混凝土的细观结构;利用非线性有限元方法从细观层次上对混凝土试件的断裂过程进行数值分析,采用3种不同骨料分布的混凝土试件分别研究了混凝土试件在单轴受拉和单轴受压时的破坏机理。研究结果表明:混凝土的断裂主要发生在骨料与砂浆的粘结面上;试件在单轴受拉时的裂纹沿垂直于最大拉应力的方向扩展;而试件在单轴受压时的裂纹沿平行于最大压应力的方向扩展;数值研究还发现:裂缝的扩展方式不是直线和连续的,而是弯曲的,还出现裂纹交错分叉以及所谓的裂缝面桥现象。

Numerical Analyses for Fracture Process and Failure Mechanism of Concrete on Meso-level

To study the relation between the meso-level damage fracture and macro-level failured concrete is an important subject for realizing the fracture mechanical properties and the failure rnechanism of concrete. The level structures of concrete were represented with random aggregate model by using Monte-Carlo mothod. The meso-level damage fracture and failure mechanism of concrete specimens were simulated with nonlinear finite element rnethod. The specimens with three different distributions were studied under uniaxial tensile and uniaxial compression respectively. The results of analyses showed that the fracture of concrete is generally along the bond of aggregate and matrix. Cracks propagate in a direction perpendicular to the maximum tensile stress when specimens of concrete are under uniaxial tensile. And cracks propagate in a direction parallel to the maximum compression stress when specimens of concrete are under uniaxial compression. The numerical analyses also found that the crack patterns in concrete are never straight and continuous. Cracks are tortuous and there are overlaps or so-called crack interface bridges.