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从结构特征出发,分析了多孔复合体的混凝土中的裂纹萌生和扩展过程。指出,在混凝土中的裂纹前端有一个微裂纹带,它可用一个起着应力传递作用的虚拟裂纹来表征。并且,提出了控制裂纹带的稳定或扩展的能量判据方程。为了描述微裂纹处由于受力状态所导致的逐步退化,引用了以损伤和弹性行为相联系的“损伤判据”。借助于形变和声发射同步的分析曲线,可确定混凝土中的无微裂纹区。
Starting from the structural characteristics, the initiation and propagation of cracks in concrete of porous composites were analyzed. It is pointed out that there is a micro-cracks zone in the front of the crack in concrete, which can be characterized by a virtual crack that acts as a stress transfer. Also, the energy criterion equation for controlling the stability or extension of the crack band is proposed. In order to describe the gradual degradation of the microcracks due to the stress state, a “damage criterion” linked with damage and elastic behavior was cited. With the help of the analysis curves of deformation and acoustic emission synchronization, the microcrack-free zone in the concrete can be determined.