雁行双裂隙类砂岩加载条件下裂纹扩展演化规律研究

为了研究裂隙岩体在荷载作用下裂纹扩展演化与破坏规律,以预制含雁行双裂隙类砂岩试样为研究对象,采用单轴压缩试验与DIC技术相结合,探究裂隙倾角和岩桥倾角对试样裂纹产生、扩展和破坏模式的影响。结果表明：(1)裂纹先从试样边界处产生,向试样中心扩展,随加载的进行,裂纹转向从裂隙尖端处产生,向试样上下端面扩展。(2)试样新生裂纹扩展演化过程、破坏模式与裂隙的倾角特征关系密切,随裂隙倾角和岩桥倾角的增加,裂纹扩展的数量分别呈现出先减少再增加后减少、先减少后增加的特点,试样破坏模式呈现出由张拉破坏向张拉-剪切复合破坏转变,但当裂隙倾角增加至90°时,试样破坏模式又呈现出张拉破坏。(3)岩桥贯通取决于其水平投影长度,当岩桥倾角为0°、30°,岩桥水平投影长度较长,岩桥未贯通,当岩桥倾角为60°、90°、120°,岩桥水平投影长度逐渐减小,岩桥发生直接贯通。研究成果可为工程设计及优化提供一定的指导意义。

Study on Crack Propagation and evolution law of quasi-sandstone containing two non-coplanar fissures under loading conditions

In order to study the crack propagation evolution and failure law of fractured rock mass under load, the prefabricated two non-coplanar fissures sandstone samples were prepared as the research object. The uniaxial compression test combined with the DIC technology was used to explore the influence of the fissure angles and ligament angles on the crack generation, propagation and failure mode of the samples. The results show that: (1) The crack first initiates from the boundary of the specimen and extends to the center of the specimen. As the loading progresses, the crack initiates at the crack tip and extends to the upper and lower ends of the specimen. (2) The evolution process and failure mode of new cracks in specimens are closely related to the dip angle characteristics of the fissures. With the increase of the fissure angle and ligament angle, the number of crack propagation shows the characteristics of first decreasing, then increasing and then decreasing, first decreasing and then increasing, and the failure mode of the specimen changes from tensile failure to tensile-shear composite failure. However, when the fissure angle increases to 90°, the specimen shows tensile failure again.(3) The transfixion of the rock bridge depends on the length of its horizontal projection. When the ligament angle is 0°, 30°, the horizontal projection length of the rock bridge is long, the rock bridge has no transfixion, When the ligament angle is 60°, 90°, 120°,the horizontal projection length of the rock bridge gradually decreases, and the rock bridge occurs direct transfixion. The research results can provide certain guiding significance for engineering design and optimization.