Abstract: The rock specimens prepared by traditional rock core drilling method have the disadvantages of unclear internal structures in the same batch and large differences in mechanical properties, and the specimens prepared by inserting joint method have the disadvantages of difficulty in controlling prefabricated joints, low precision and long cycle. 3D printing technology overcomes the deficiencies of the traditional specimen preparation methods, but its shortcomings are low strength and high plasticity of the prepared specimens. Non-jointed complete specimen A-1-1 and non-consecutive parallel four-joint specimen B-1-1 were produced using 3D printing technology. Then vacuum drying and uniaxial compression tests were carried out on these specimens. Moreover, CT scanning test and internal fracture 3D reconstruction were performed on specimen B-1-1. We obtained the stress-strain curve, apparent fracture mode of the specimens and internal crack distribution of specimen B-1-1 after uniaxial compression. Experimental results indicate that: the comparison between the stress-strain curves of specimen A-1-1 and the undried specimen shows that the strength and plastic deformation of vacuum-dried specimens have been greatly improved, which provides references for the applicability of 3D printing specimen in rock mechanics field. The stress-strain curve of specimen A-1-1 is similar to that of the rock, and the apparent cracking mode of specimen A-1-1 is similar to that of the medium sandstone, indicating 3D printing specimen can be used in the mechanical study of similar rock. The ‘wing-shaped flat-necked funnel-shaped’ fracture mode is the main failure mode to lose the bearing capacity of the non-consecutive parallel four-joint specimen, and the generation, expansion, and penetration evolution of cracks under uniaxial compression are the combination of the complex tensile-shear group. Besides, the internal fracture mode and apparent fracture mode are different, and the apparent fracture mode cannot accurately characterize the internal fracture mode.

Key words: 3D printing technology, non-consecutive joint rock mass, CT scan, 3D reconstruction, fracture evolution