Failure mechanisms and mechanical behavior of wedge-containing tunnel roof rock mass under biaxial loading

• Wedge block geometry significantly influences the mechanical behavior and failure modes of arched tunnel roofs under biaxial loading. • Support measures are more effective in enhancing the strength of stable wedge blocks (T3, T4) compared to unstable ones (T1, T2). • Failure modes are classified as rock-dominated, wedge-dominated, or co-dominated, with cracks initiating near the wedge and propagating outward. • Unsupported conditions lead to high stress differences and localized shear failure, while support alters crack distribution and stress redistribution.