层理灰岩抗拉力学参数各向异性及破裂特征分析

Analysis on anisotropic tensile parameters and fracture characteristics of limestone with different dip angles

山体斜坡在自重荷载或卸荷作用下常表现为侧向受拉,拉裂缝的形成及展布方向与层面产出状态密切相关。为探讨层理倾角对岩体抗拉力学特性与宏-细观破裂特征的影响,以三叠系大冶组中厚层状灰岩为研究对象,对0,15°,30°,45°,60°,75°,90°共7种倾角层理灰岩岩样进行巴西劈裂试验,并结合高精度三维激光扫描技术,获得了岩样拉伸力学参数和破裂面线粗糙度、盒维数随层理倾角的变化规律。研究结果表明:随着层理倾角的增加,灰岩抗拉强度与拉伸模量逐渐降低;张拉裂缝呈现出基体拉裂-拉剪复合-弱面层理张拉的破裂变化趋势;且最终破坏形态可分为直线型、月牙形与弧形;破裂面线粗糙度与盒维数值随层理倾角增加而先增大、后减小、再增大,起伏粗糙度与破裂面张拉作用大小呈正相关、与破裂面剪切作用大小呈负相关关系。研究结果可为进一步完善层状岩体张拉破坏内部演化机制研究提供参考。

Mountain slopes often show a state of lateral tension under self-weight load or unloading, and the formation and spreading direction of tensile cracks are closely related to occurrence of rock plane.In order to explore the influence of bedding dip on the tensile mechanical properties and macro-micro fracture characteristics of rock masses, medium-thick layered limestone of the Triassic Daye Formation with 0°,15°,30°,45°,60°,75°,90° seven dip angles were subjected to Brazil splitting test.By using high-precision three-dimensional laser scanning technology, the rock sample tensile mechanical parameters, linear roughness of fracture surface, and the box dimension changing law with the bedding inclination angle were clarified.The results show that with the increase of bedding angle, the tensile strength and tensile modulus of limestone decrease gradually, and the tensile crack development presents a trend of matrix tension crack, tension-shear composite and weak plane tension.The ultimate failure mode can be divided into straight line, crescent and arc.The linear roughness and box dimension of fracture surface first increase then decrease and increase with the increase of bedding angle.The undulating roughness has a positive correlation with the tensile action of fracture surface and a negative correlation with the shear action of fracture surface.The research results can provide a reference for further study on the internal evolution mechanism of tension failure of layered rock.