<p>In deep-buried tunnel engineering, the complex three-dimensional geometry of underground openings can lead to a wide range of orientations between the principal loading direction and the shotcrete–rock interface. However, prior studies have predominantly considered configurations in which the loading direction is normal to the interface, leaving the mechanical response of shotcrete–rock combined bodies (SRCBs) with inclined interfaces insufficiently understood. This study addresses this critical research gap by conducting triaxial compression tests on SRCBs consisting of granite and shotcrete (prepared with crushed-limestone aggregates and reinforced with polypropylene fibers) with five different interface inclinations (0°, 30°, 45°, 60° and 90°) under four confining pressures (0, 5, 10 and 20 MPa). The experimental results showed that the failure modes of combined bodies could be distinctly categorized into three different types. The peak strength of the combined bodies exhibited an initial increase followed by a decrease as the interface inclination increased, while it increased with rising confining pressure. With an increase in confining pressure, the elastic modulus increased, whereas Poisson’s ratio decreased. Besides, the combined body showed its lowest elastic modulus and Poisson’s ratio at an interface inclination of 60°. Except for this case, larger inclinations generally resulted in higher values of both parameters. In addition, the internal friction angle and cohesion reached their maximum values at 90°. For inclinations below 60°, both parameters decreased monotonically with increasing inclination. Furthermore, discrete element models of SRCBs with varying interface inclinations were established under four different confining pressures, and their predictive capability for the triaxial stress–strain response and failure characteristics was verified. These findings can provide useful guidance for the design and safety assessment of deep-buried tunnels in complex geological engineering.</p>