用数字图像相关技术进行红砂岩细观裂纹损伤特性研究

STUDIES ON MICROCOSMIC CRACK DAMAGE PROPERTIES OF A RED SANDSTONE WITH DIGITAL IMAGE TECHNIQUE

通过对红砂岩试样应变响应和表面裂纹图像的同步观测试验,以及试样表面细观裂纹萌生、扩展图像信息的采集和量化方法的研究。提出了用数字图像相关技术处理不同含水状态下红砂岩试样动态变形过程中的灰度分布图;并去除微裂纹,探讨了红砂岩动态损伤状态与其宏观力学之间的关联。为了获得试样微观预制裂纹扩展的定量描述,引入裂纹损伤度与损伤张量2个物理量,定量评价了含水状态下红砂岩预制细观裂纹动态渐进扩展损伤特性,进一步了解了单轴压缩状态下细观裂纹扩展的演化规律。

This study aims to investigate experimentally the relation between dynamic damage state and mechanics responses of a red sandstone. Cracks and holes on the surface of specimen are observed and recorded synchronously with deformation responses. The images of cracking of specimen in different water content states are analyzed by a digital image technique, and quantitative results for surface cracking process are obtained. In order to obtain the quantitative description of microcosmically prefabricated cracks development, two physical quantities, of damage tensor and crack degree, are proposed for quantitatively estimating dynamic and gradual damage development of the red sandstone using microcosmic cracking in water content state. Further understanding about the damage evolution law of red sandstone under single axis compression though applying microstructure method is also obtained.