基于数字图像处理的含缺陷混凝土破裂过程研究

Research on failure process of concrete with defects based on digital image processing

混凝土破坏规律受其缺陷的影响,为了从细观尺度研究含缺陷混凝土破坏规律,基于数字图像处理技术表征混凝土骨料形状、大小及空间分布,运用RFPA2D-DIP软件构建混凝土真实细观模型并进行单轴压缩试验,研究了含不同缺陷混凝土的破坏规律。试验结果表明:相比完整试件,含缺陷试件强度更低,破坏过程应力跌落次数更多,其初始裂纹在预制裂隙及孔洞两端萌生,缺陷与新裂纹的贯通最终导致试件破坏;混凝土中同时存在孔洞和裂隙时,孔洞与裂隙相互影响并形成应力集中的岩桥区域,当孔洞直径不变时,随着裂隙长度增加,试件峰值强度下降,在同一裂隙长度下,随着孔洞直径增大,混凝土峰值强度降低。

The failure law of concrete is affected by its defects.In order to study the failure law of concrete with defects from meso-scale,based on digital image processing technology to characterize the shape,size and spatial distribution of concrete aggregate,the real meso-model of concrete is constructed by RFPA2D-DIP software and uniaxial compression test is carried out to study the failure law of concrete with different defects.The test results show that the strength of the specimens with defects is lower than that of the complete specimens,and the number of stress drops during the failure process is more.The initial cracks initiate at both ends of the prefabricated cracks and holes,and the penetration of defects and new cracks eventually leads to the failure of the specimens.When there are holes and cracks in concrete,the holes and cracks interact and form each other.In the stress concentrated rock bridge region,the peak strength decreases with the increase of the crack length when the hole diameter remains unchanged.In the same crack length,the peak strength of concrete decreases with the increase of the hole diameter.