Mechanisms of long-term deformation and failure in deep hard fractured rock roadways: A case study on blasting-induced effects

Long-term deformation and failure in deep hard fractured rock roadways are significantly aggravated by the combined effects of high in-situ stress and frequent blasting disturbances. However, the mechanisms by which repeated blasting accelerates degradation in highly fractured rock masses remain inadequately understood. This study investigates the 790 m level of the Jinchuan No. 2 Mine using a multi-scale monitoring system incorporating 3D laser scanning, borehole imaging, multi-point extensometry, and vibration sensing to track the spatiotemporal evolution of surface deformation and internal cracking. Field observations revealed distinct asymmetric and non-uniform deformation and failure patterns. Deformation and structural degradation predominantly evolve along the direction of maximum principal stress (σ₁), while support structures oriented perpendicular to σ₁ are prone to buckling. In unloading relaxation zones, primary cracks open and are highly sensitive to blasting vibrations, whereas in stress-concentrated zones with compacted crack networks, the influence of vibrations is minimal. The results identify blasting-induced crack propagation as a key driver of long-term degradation. Distinct stress regimes regulate fracture evolution differently, highlighting the necessity to minimize excavation-induced failure and control dynamic disturbances to enhance long-term stability. These findings improve our understanding of excavation–blasting interactions in deep fractured rock masses and support the development of more effective and adaptive support strategies.