基于CT的岩石三维裂隙定量表征及扩展演化细观研究

Quantitative characterization and mesoscopic study of propagation and evolution of three-dimensional rock fractures based on CT

岩石破裂是裂纹萌生、扩展演化直至贯通的过程,为了研究受载岩石发生变形破坏时其内部裂纹动态扩展演化过程,利用工业CT对岩石破裂过程进行阶段性观测扫描,通过CT图像堆栈矢量化处理构建岩石三维裂隙模型,并对裂纹结构特征参数进行统计分析,定量化表征岩石破裂过程中裂纹扩展情况。在此基础上,提取裂纹扩展路径上的局部破坏形态特征,结合岩矿鉴定试验进行细观尺度分析研究。研究结果表明:利用裂隙体积V、表面积S及分形维数D等参数可以将三维裂隙扩展过程量化,且参量呈现基本不变—小幅增大—大幅激增的变化规律;CT切片图像中裂纹面积可以表征岩石局部裂纹扩展特征,且与同阶段三维裂隙的扩展演化特征相对应;岩石细观结构对裂隙扩展影响较大,裂隙扩展遇到砾石将形成绕砾扩展、穿砾扩展及分叉扩展3种方式。该研究成果将为岩石失稳破坏、工程岩体致灾预警工作提供研究基础。

Rock rupture refers to the process of crack initiation,propagation and coalescence.In order to study the dynamic propagation and evolution process of internal cracks in rock subjected to deformation and failure,industrial CT was used to conduct phased observation and scanning of the rock rupture process,and a three-dimensional rock fracture model was constructed by vectorization of CT image stack.The characteristic parameters of the crack structure were statistically analyzed to quantitatively characterize the crack propagation during the rock rupture process.On this basis,the local failure morphology characteristics on crack propagation path were extracted and the rock and mineral identification experiment was combined for meso-scale analysis.The research results show that the three-dimensional fracture propagation process can be quantified using parameters such as fracture volume V,surface area S,and fractal dimension D,and the parameters experience a change law of"basically unchanged–small increase–surge".Based on the CT slice images,the crack area can characterize the local crack propagation characteristics of the rock,and it corresponds to the expansion and evolution of the three-dimensional cracks at the same stage.The mesostructure of the rock has a great influence on the crack propagation,which form the extension around the gravel,through the gravel,and bifurcation when encountering gravels.The research results will provide a research foundation for rock instability failure and disaster warning of engineering rock mass.