The laboratory results of axial compression test with different angle between loading direction and normal direction of bedding plane are introduced. Due to the high density of bedding plane in the schist, the test result show a significant anisotropic in uniaxial compressive strength and Young's Module. The results of strength and Young's Module when bedding plane is horizontal are larger than the test results of any other bedding plane angle. It's difficult to simulation the anisotropic strength and deformation response during the compression test with constitutive model. The bonded particle model and smooth-joint model in PFC (Flow Particle code) was used to mimic schist. The rock host of schist was simulated by parallel-bonded particle, and the high density bedding plane was simulated by smooth-joint model. Axial compression tests with different load angle was simulated, a good agreement was observed between experiment results and simulation results.
In general, the most anisotropic elastic behaviour of material is described by 21 independent elastic constants. The orthotropic isotropic reduce the independent elastic constants from 21 to 9, and the transversely isotropic model is characterized by 5 independent elastic constants. Transversely model is the most popular model for schistose rock like schist, gneiss, shale, etc.[1–4]
In order to determined 5 independent elastic constants, at least 3 specimens that bedding plane inclined parallel, vertical, and at an angle are required[5]. Previous research has established ways to minimize the laborious task of preparing multiple specimens, one approach is to reduce the 5 independent elastic constants to four by using Saint-Venant's empirical equations for shear modulus in the plane normal to the isotropic plane[6]. These empirical equation is not acceptable for schistose rock[7].
Although significant achievements have been achieved over the past 40 years, there is no standard method has been suggested to determine the elastic constants of schistose rock[8]. In this paper, we firstly introduce the experiment study of a typical schistose rock: Danba schist, then calculating the 5 independent elastic constants of Danba schist based on experiment results. The main objection of this study is to simulation the uniaxial compressive test by using PFC and compare the simulated results with laboratory test result and analytical results.
