含缺陷混凝土细观损伤破坏过程的数值模拟

Numerical simulation of meso-damage and failure process of concrete with defects

将混凝土看成由骨料、砂浆、界面和缺陷等组成的四相复合材料,通过圆形孔隙和币状裂隙表征缺陷,采用应力-裂缝宽度模型反映骨料、砂浆和界面的非线性本构关系,得到了轴拉荷载作用下试件破坏过程的应力-应变全曲线和弯拉荷载作用下的荷载-位移全曲线,并对圆形孔隙和币状裂隙及其含量对混凝土破坏过程和极限荷载的影响进行了分析.结果表明:圆形随机骨料试件的极限荷载高于任意多边形骨料试件的极限荷载,缺陷会弱化混凝土宏观力学性能;与圆形孔隙相比,币状裂隙对混凝土的破坏作用更大.

The concrete was regarded as a kind of four-phase composite material consisting of aggregate,mortar,interfacial transition and random micro-defects.The defects were characterized as circular pores and penny cracks.The stresscrack width model was employed to depict the nonlinear constitutive relationship among the aggregate,mortar and interfacial transition.The stress-strain curves of specimens during failure process under uniaxial tensile load as well as the load-displacement curves under bending tension were obtained.The influences of the circular pores and penny cracks as well as their contents on the failure process and the ultimate load of concrete were analyzed.The results show that the ultimate load of concrete specimens with circular aggregate is larger than that with arbitrary polygon aggregate.The defects can weaken the macro-mechanical properties of concrete.The penny cracks are more disadvantageous than the circular pores.