Influence of intermittent opening density on mechanical behavior and fracture characteristics of 3D-printed rock

To investigate the influence of intermittent opening density on the mechanical behavior and fracture charac-teristics of rock, sand 3D-printed specimens containing different opening numbers are prepared using quartz silica sand and furan resin adhesive as printing substrates. Uniaxial compression testing is performed on these rock-like specimens. Based on digital image correlation (DIC) technology, a methodology for identifying crack types and evaluating rock damage is proposed to quantify the mechanical mechanism of crack evolution during loading. The experimental results are verified and explained using the rock failure process analysis (RFPA) code. The results show that with increasing intermittent opening density, the stress-strain curves of the specimens are similar. Meanwhile, the increase in intermittent opening density causes the stress field distribution of the specimen to change, which in turn leads to a decrease in the uniaxial compressive strength and elastic modulus. The types of cracks around the opening can be grouped into tensile cracks (T) and shear cracks (S), and the coalescence modes of the rock bridge between the openings can be grouped into shear coalescence (C1) and traction coalescence (C2). As the intermittent opening density increases, the coalescence type between openings changes from C1 to C2, and the overall failure pattern is converted from tensile-shear failure to tensile failure. The damage factor (Df) evolution is closely related to the intermittent opening density of the specimens. A one-way exponential decay correlation between the stress ratio and the damage factor is found. The above study is ex-pected to deepen the understanding of the deformation and fracture mechanism of rock masses with openings and to provide a reference for the application of 3D printing technology in the rock mechanics field.