Anisotropy Study On Engineering Geological Properties Of Slate In Dam Site Area Of Bailongjiang Water Diversion Project

Silurian sandy slate,carbonaceous slate and phyllite are the main exposed lithology in the dam site of Bailongjiang Water Diversion Project.This kind of rock has obvious layered structure,which will lead to the anisotropy of its physical and mechanical properties and deformation and failure characteristics.Therefore,it is of theoretical and practical significance to study the engineering geological properties of layered rocks in this area and analyze their anisotropy.In this paper,taking the slate samples in the dam site of Bailongjiang Water Diversion Project as the research object,the relationship between P-wave velocity and layered structural plane is studied by combining P-wave velocity test with theoretical derivation.Uniaxial compression test and acoustic emission monitoring were carried out to explore the anisotropy of physical and mechanical properties of slate.The anisotropy of tensile characteristics of slate is analyzed by numerical simulation software and Brazilian splitting test.The results show that:(1)Layered structural plane has great influence on the measured value of longitudinal wave velocity,and there are obvious differences in refraction,reflection and energy dissipation when longitudinal wave passes through layered structural plane.Among them,the longitudinal wave velocity of the slate gets the minimum value at 45 and the maximum value at 0.(2)The uniaxial compressive strength and elastic modulus of slate show a "U" trend with the angle of layered structural plane,and both of them get the lowest values around 45.(3)The failure modes of rock under uniaxial compression are mainly divided into three types:tensile splitting failure along bedding plane,shear sliding failure along bedding plane,shear failure through bedding and along bedding,tensile shear through bedding and composite failure along bedding.The anisotropy is obvious.(4)Compared with the loading direction β,the angle φ of layered structural plane has a greater influence on the tensile properties of slate.Under the above conditions,the tensile strength and failure mode of slate are obviously anisotropic.