Anisotropy study based on uniaxial compression experiments

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Abstract Due to the striated sedimentary structure of laminated shale and the weak cementation between the layers, the damage patterns of laminated shale with different laminar angles have obvious anisotropy after being damaged by uniaxial compression experiments. In this paper, numerical simulations of uniaxial compression experiments are carried out based on GDEM-PDyna on laminated shale with laminar angles (0°, 15°, 30°, 45°, 60°, 75°, 90°) to explore the anisotropy of compression parameters of laminated shale. The results show that: (1) the uniaxial compressive strength of laminated shale with the increase of the angle of the laminate shows a “U” type change rule which decreases first and then increases, and the uniaxial compressive strength is the smallest when the angle of the laminate reaches 60°; (2) the Poisson’s ratio of the specimen of laminated shale with the increase of the angle of the laminate shows a process which decreases first and then increases, and the change of Poisson’s ratio with the angle of the laminate has the same relationship with the elasticity of the specimen, and it is the same as the change of the compression parameters. The change of Poisson’s ratio with the increase of lamination angle and the change of modulus of elasticity show a similar law, all of them have experienced the “U” type change rule of decreasing first and then increasing, and all of them reach the minimum value when the lamination angle is 30°. (3) The brittleness index of the laminated shale samples showed a “stepwise” decrease with the increase of the laminated angle.