基于CT扫描的致密砂岩脆性破坏裂纹扩展规律研究

岩石在荷载作用下产生宏观破坏,其破裂面细观形态变化可以直接地反映出结构破坏特征。目前,常采用扫描电镜法、透镜法和CT扫描技术对岩石细观结构进行表征。运用CT扫描技术对典型脆性岩样单轴压缩破坏后破裂面及全断面进行扫描,获取全断面的细观形态,分析和总结了典型脆性岩样破坏细观裂纹扩展的发展规律:每一条独立裂纹都以一恒定曲率半径系数K随层位向试样内部扩展,直至裂纹曲率半径趋近于无穷。此时若无其他因素影响,其曲率半径则不会再随层位继续扩展;并通过分析定义出岩石脆性破坏状态时裂纹的聚集域和非聚集域,同时根据能量守恒定律得出了衍生裂纹及新次生裂纹产生的判据。

Crack Evolution of the Tight Sandstone of Brittle Failure Based on CT Technology

The tight sandstone specimens of brittle failure after uniaxial compression is scanned based on CT technology,and the images of the various types of crack brittle failure generated along the hierarchy from top to bottom are analyzed and summarized systematically to show the development regularity of diffusion.The results show that each individual crack will propagate within the specimen with layer orientation based on a constant curvature coefficient K,until the crack curvature tends to infinity.The crack reaches a steady state if there is no other factors.There is a trend of aggregation when the cracks develop along the central axis from the two ends of the specimen to the interior of the specimen,which defines the domain of crack aggregation and the non aggregation of cracks.With the direction of crack propagation and the derivative of the secondary crack,crack formation with derivative diffusion speed with the rapid development of secondary cracks and they will coincide,and the development of corresponding growth will slow at the same time.According to the law of conservation of energy,the new criterion of derivative crack and secondary crack is produced.