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采用医用计算机层析(CT)设备与其配套的三轴压力仪,对压缩条件下岩石细观损伤过程进行了动态观测。以CT数为基础定义了岩石密度损伤增量,提出了CT数与岩石密度损伤增量的定量关系式。采用CT图像分析了岩石细观损伤过程;利用提出的岩石密度损伤增量定量地分析了峰值强度前的裂纹萌生、扩展、连通的细观损伤演化规律。发现岩石在峰值强度前普遍经历压密和扩容两个阶段,不同层位或同一层位的不同部位损伤具有明显的差异性,即在同一应力作用下各部位的压密程度和扩容状态是不同的。密度损伤增量异常带是微裂纹萌生带,在密度损伤增量与应力关系曲线上的拐点是岩石局部破坏的起始点。
Using the medical computer tomography (CT) equipment and its supporting triaxial pressure gauge, the microscopic damage process of rock under compression was dynamically observed. Based on the CT number, the increment of rock density damage is defined, and the quantitative relation between the CT number and the increment of rock density damage is proposed. The meso-damage process of rock was analyzed by CT image. The evolution of meso-damage of crack initiation, propagation and connectivity before the peak intensity was quantitatively analyzed by using the increment of rock density damage. It is found that the rocks generally experience two stages of compaction and expansion before the peak intensity. There are significant differences in damage between different layers or in different parts of the same layer, that is, the degree of compaction and expansion of each part under the same stress are different of. Incremental density damage anomalous zone is a micro-crack initiation zone. The inflection point on the curve of incremental density-stress relationship is the starting point of local rock failure.