混凝土损伤断裂的三维细观数值模拟

3-D mesoscopic numerical simulation of concrete damage and fracture

提出一种在细观层次建立混凝土三维随机骨料随机力学参数模型的方法。将损伤力学与计算力学相结合,基于ANSYS软件平台进行二次开发,建立2组混凝土立方体湿筛试件的数值模型:第1组模型模拟3种不同的骨料随机分布;第2组模型模拟混凝土各相材料主要力学参数的随机性,分别假定其参数符合对数正态分布和Weibull分布。通过对这2组模型的轴压进行模拟,揭示混凝土在轴向压力作用下单元的渐进损伤和裂缝的萌生与扩展过程。研究结果表明:数值模拟得到的混凝土立方体抗压强度与试验测得的抗压强度较接近;骨料的随机分布会影响试件裂缝产生的位置和扩展路径,但其对试件承载力的影响不大;混凝土各组成相材料参数的非均匀性降低了试件的极限承载力,采用Weibull分布能较好地表征材料参数非均匀性的影响。

On the meso-level,a method for establishing 3-D numerical model with random distribution of aggregate location and mechanical parameters was put forward.Based on damage mechanics and computational mechanics,two groups of numerical models of wet-screened concrete cube specimens were established with ANSYS software,i.e.,the first group of models was designed to simulate three kinds of aggregate random distribution with the same gradation,and the second group of models was designed to simulate the random distribution of main material parameters of phases that composed concrete.By the numerical axial compression simulation of the two groups of models,the gradual process of damage crack appearance and the growth of concrete were revealed.The results show that the cubic compressive strength of concrete by numerical simulation approximates to that by physical test.The random distributing of aggregate location has influence on the generating location and expanding paths of crack,yet it has slight influence on the carrying capacity of samples.The material parameters heterogeneity of phases,which can be characterized well by Weibull distribution,reduces the carrying capacity of specimens.