Application of 3D printing technology in physical modelling in rock mechanics

Although the application of 3D printing technology in physical modelling in rock mechanics is still at the preliminary stage of exploration, its reproducible production of specimens with complex internal structures is impossible for the conventional test method. At present, 3D printing technology is difficult to be applied in physical modelling in rock mechanics. The reasons are caused by the low strength of 3D specimens that is even lower than the weakest existing rock and the strong ductile behaviour of the 3D printed specimens. The main objectives of this study are to explore the effects of the drying time after printing and binder saturation level on the strength of the 3D printing specimens during UCS tests and Brazil disk split tests. Based on the test results, the study puts forward a set of optimum printing parameters, which can greatly enhance the strength of 3D printing specimens and reduce their ductile behaviour in the test. By changing the inclined angles of the printing layers, the specimens can be used to simulate the anisotropy of natural bedding joint rock. The results show that as the inclined angles increases, the uniaxial compressive strength of the 3D printing specimens decrease first and then increase, showing a U-shape trend. Besides, the tensile strength shows an obvious anisotropy with changing the printing directions. The results are similar to the previous results of natural bedding joint rock. The findings of this study verifies the feasibility of 3D printing technology in the experimental study on rock mechanics.