Induced mechanism of tunnel rockbursts based on dynamic buckling of rock plates

Abstract

Rockburst, characterized by a sudden and violent rock failure resulting in the expulsion of rock from its surroundings, poses a significant threat to the safety of tunnel excavation operations, often causing property damage and injuries to workers. Buckling has been identified as a critical mechanism leading to rockbursts. Seismic events or blasting can induce rockbursts when stress waves reach the free surface of underground openings. This paper aims to investigate the induced mechanism of tunnel rockbursts based on the dynamic buckling of rectangular rock plates. As a rock stress wave approaches a tunnel sidewall, it decomposes into perpendicular and parallel component loads relative to the free surface. The perpendicular stress reflects off the free surface, forming a rectangular thin plate of rock. The parallel stress triggers parametric resonance in the plate, resulting in a tunnel rockburst. An illustrative example of tunnel sidewall rockbursts in Jinping II hydropower project, China, is provided to study the effects of stress wave amplitude and frequency, static and dynamic components, rock damping, multiple frequencies, and vibration modes. Based on this mechanism analysis, recommendations are proposed to mitigate the risk of tunnel rockbursts. The research offers a plausible explanation for the heightened frequency and severity of rockbursts in Tunnel Boring Machine tunnels compared to New Austrian Tunneling Method tunnels at the Jinping II project for the first time.