混凝土四相复合模型的三维细观破坏模拟

3D Meso-scale Failure Simulation of Four-phase Composite Concrete

考虑到混凝土内部细微裂隙的存在对混凝土强度和变形的重要影响,提出将混凝土视为砂浆、骨料、界面和随机缺陷组成的四相复合材料模型。混凝土细观单元服从应变空间内增量形式的弹塑性损伤本构,采用破坏单元网格消去法模拟混凝土裂纹扩展,数值模拟了三维混凝土单轴压缩和不同均质度试样的单轴拉伸弹塑性损伤破坏过程。结果表明:文中建立的混凝土四相复合材料模型中增加随机缺陷的模拟,一定程度上符合混凝土成形实际情况;随机缺陷的体积百分比是决定弱化混凝土宏观强度程度的主要因素;均质度低的单轴拉伸试样裂纹咬合明显,均质度高的试样断裂更清晰,数值模拟结果与试验结果较吻合。

Taking into account the influence of the internal micro cracks on the strength and deformation of concrete, a four-phase composite material model was proposed, in which it included mortar, aggregate, interface and random defects. Meso-scale unit in concrete was subjected to elastic-plastic damage constitutive of increments form in strain space. With the simulation of mesh concrete crack growth by damage elimination, the damage processes of concrete under 3-D uniaxial compression and the elasto-plastic damage process of concrete under uniaxial tension with heterogeneous specimen were obtained. It was shown that the proposed four-phase model added the simulation of random defects, with which it was more appropriate to the actual situation in concrete forming. The percentage of random defects in volume was the key to determine the weakening degree of macro-strength of concrete. The cracks occlusion was obvious for the lower homogeneous uniaxial tension specimen and the fracture was clearer for higher homogeneous specimen. The simulation results was in good agreement with test results.