板裂千枚岩微观结构与力学性质

Microstructure and Mechanical Properties of Broken Phyllite

为了研究板裂千枚岩的微观结构及力学性质,以汶川—马尔康高速公路沿线典型的板裂千枚岩为研究对象,进行了X衍射,薄片鉴定和单轴、三轴压缩试验。结果表明:1)板裂千枚岩微观结构和矿物成分比较复杂,具有明显的脆、塑性变形和裂隙,结构稳定性差;2)板裂千枚岩的各向异性明显,结构面夹角从0°到90°,板裂千枚岩的弹性模量、抗压强度、黏聚力和内摩擦角先减小后增大,呈V型分布规律;3)板裂千枚岩的破裂模式与结构面夹角和围压的大小密切相关,其破裂模式共有顺结构面的张拉劈裂破坏、顺结构面的剪切滑移破坏、Y型张拉-剪切复合破坏、顺结构面和贯穿结构面的复合张剪破坏、贯穿结构面的剪切破坏5种类型;4)随着围压的增大,不同结构面夹角试样的强度、变形参数和破裂模式的各向异性逐渐减弱;5)最大主应力与结构面的组合方式控制着岩石的破裂模式和力学性质,这是板裂板裂千枚岩显示各向异性的根本原因。

In order to study microstructure and mechanical properties of broken phyllite,the typical broken phyllite along the Wenchuan-Maerkang expressway was taken as the research object.X-ray powder diffraction,thin slice identification,uniaxial and triaxial compression tests were carried out.The results show that:1)The microstructure and mineral components are very complex.Most of the rocks have obvious brittle,plastic deformations and fractures with poor structural stability.2)Significant anisotropy of broken phyllite was observed.Some mechanical parameters increased after the first decrease,such as the elastic modulus,compressive strength,cohesion and friction angle.These mechanical parameters showed a V-shape when the angle varied from 0°to 90°.3)The failure modes of broken phyllite are closely related to angles and the confining pressure,which can be summed up in five types:tensile splitting along structural plane,shearing slip failure structural plane,Y type tensile-shear compound failure,compound shear failure across and along structural plane,and shear failure cross structural plane.4)With the increasing of confining pressure,the strength,deformation parameters and failure modes of rock samples gradually weakened.5)The combination of the maximum principal stress and the structural plane controls the failure mode and mechanism of rock,and it is the fundamental reason for the anisotropy of broken phyllite.