The presence of joints and other types of discontinuities has a significant effect on the mechanical behaviour of rock, thereby fundamentally influencing the stability of rock excavations. The main challenge associated with the experimental research on jointed rock lies in the difficulty of sample preparation to represent the influence of discontinuities on the mechanical behaviour of the rock material. In this study, 3D printing is used as tool to examine the mechanical behaviour of rock-like samples made from sand powder. Artificial samples are prepared and tested in laboratory to verify the suitability of sand powder for simulating soft rock. Further 3D printed samples with different joint geometries (dip angle, aperture, and trace length) were tested, and the effect of each joint parameter on the sample macroscopic mechanical behaviour is investigated. As expected, the results show that the dip angle has the strongest effect on uniaxial compressive strength. The dominant failure mechanism tends to switch from tensile to shear failure with the increase of the dip angle. The influence of aperture and trace length on the mechanical behaviour is also determined and linked to the dip angle. Test results were further validated and analyzed with numerical modelling and analytical methods. The results of this study demonstrate the applicability of sand powder 3D printing as a suitable method for the simulation of soft rock mechanical behaviour. The methodology presented in this study could be further extended to other applications in rock mechanics.

Sand powder 3D printing,soft rock,joint rock mechanics,joint geometric parameters,experimental research