<p>Engineering practice has demonstrated that tunnel surrounding rocks contain numerous defects, such as joints and fractures. Under in-situ stress, these fractures are prone to propagation and interconnection, leading to a significant degradation in the mechanical properties of the surrounding rock. Therefore, it is essential to investigate the propagation and failure mechanisms of joints with different geometries under stress. Previous studies have largely overlooked the synergistic effects of multiple joint parameters, particularly the influence of roughness on open joints. Therefore, this study employed 3D printing technology to fabricate open non-persistent rock joints. Digital Image Correlation (DIC) was utilized to analyze the multi-factor synergistic effects on joint strength, fracture evolution, and failure modes. The results indicate that in open non-persistent rock joints, both the compressive strength and elastic modulus exhibit a positive correlation with the joint inclination angle. From 0° to 90°, these properties increased by 15.43 MPa and 0.412 GPa, respectively. Higher Joint Roughness Coefficient (JRC) values and shorter joint lengths enhance these mechanical properties, with joint length having a particularly significant impact. The maximum improvement (14.03 MPa) occurred at 45°. Progressive fracture evolution initiates from strain localization at the joint tip, ultimately leading to penetrating failure through crack initiation, propagation, and coalescence. Notably, specimens with a 90° inclination did not exhibit a clear progressive failure pattern, showing no observable precursors before failure. Samples with 0°, 60°, and 90° inclinations failed exclusively under tensile-dominated mechanisms, regardless of JRC and length variations. In contrast, 45° specimens failed via a tensile-shear composite mechanism, while 30° specimens transitioned to this mixed mode from tensile-dominated mechanisms under increased joint length or reduced JRC conditions.</p>