基于细观力学的混凝土轴向抗拉性能数值模拟

采用基于伸缩因子的圆形覆盖方法建立更贴近于真实情况的一系列二维随机骨料模型,采用塑性损伤模型系统地对比分析了二维随机骨料模型在不同骨料形状、骨料粒径搭配、初始缺陷、界面层厚度、界面层及砂浆强度等情况下的单轴拉伸性能.结果表明,拉伸破坏首先出现在最为薄弱的界面层;骨料形状的不同对试件拉伸性能影响较大;界面层厚度对混凝土试件脆性有所影响,对其他性能影响较小;相同试件初始缺陷的增加会导致试件弹性模量、极限抗拉强度及峰值拉应变的减小;界面强度与骨料比例、形状、初始缺陷等对混凝土试件拉伸性能影响最大;本方法可有效地模拟混凝土轴向抗拉,揭示混凝土裂纹扩展的方式及过程.

Numerical simulation of concrete axial tensile performance based on mesomechanics

Round cover method based on extension factor was used to establish a series of two-dimensional random aggregate model which are more closer to the real situation.The plastic damage model was adopted to systematically compare the uniaxial tensile properties of the two-dimensional random aggregate model with different aggregate shapes,distributiong of aggregate particle sizes,initial defects,the interface layer thicknesses,the strengths of mortar and interface layer.The results show that the tensile failure first takes place in the weakest interface layer;the shape of concrete aggregate has obvious influence on the tensile property of specimens;the thickness of interface layer has some effect on the brittleness of concrete specimens,but little effect on other properties;with the increase of initial defects of the same specimens,the elastic modulus,ultimate tensile strength and peak tensile strain decrease;the strength of the interface and the ratio,shape,initial defects of aggregate have the most great influences on concrete specimens.The method proposed in this paper can simulate concrete axial tensile behavior effectively and reveal the way and process of the development of concrete cracking.