Study on the Anisotropic Shear Strength of Rough Joint via 3D Scanning, 3D Printing, and 3D Discrete-Element Modeling

The anisotropic shear strength of rough joints is examined from both experiments and numerical simulations in this paper. The rough joints in the experiment are prepared by combining 3D laser scanning and 3D printing technology. The direct shear tests are conducted in eight shear directions under constant normal load condition (CNL) with the normal stress of 0.2, 0.5, and 1.0 MPa. The dramatic variation of shear strength in different shear directions is observed from experimental results. Meanwhile, the numerical simulation based on the three-dimensional discrete-element method (DEM) is conducted, in which, the method to generate the identical rough joint by connecting triangular walls is proposed. With the calibrated microparameters from the unconfined compression test and direct shear test, the anisotropic shear strength is also observed in the numerical simulation, which is consistent with the experimental result. Accordingly, the topography anisotropy of the rough surface is analyzed, and the statistical parameter, Z(2)(theta), is found closely related to the anisotropic shear strength of rough joints. Based on this, the Barton model is modified to estimate the shear strength of artificial joints with an anisotropic effect involved. (C) 2022 American Society of Civil Engineers.