Shear behavior of synthetic rough jointed rock mass with 3D-printed jointing

Preparation of laboratory samples that have surfaces with complex but repeatable roughness distributions to study the mechanical behavior of jointed rock mass has been a challenge for experimental studies. In this paper, an innovative rough discrete fractures network (RDFN) model was proposed. Three-dimensional (3D) printing technology was used to generate synthetically jointed rock specimens while considering joint roughness and geometry. The size effect of shear behaviors under direct shear tests was discussed on the synthetic specimens described as rough discrete fracture network (RDFN) model, discrete fracture network (DFN) model, and intact specimen. According to the results, the shear strength of the 3D-printed jointed rock specimens was apparently lower than that of the intact rock specimens. The shear strength of the RDFN models, which considered joint roughness, was higher than that of the DFN models. The shear strength decreased with increasing specimen size for both the RDFN and DFN models and the fracturing patterns were greatly influnced by the joint geometry and distribution. The joint roughness is found important for the shear behaviors and should not be neglected when modeling the fractured rock mass.