基于预应力最佳轴比椭圆形隧洞的岩爆防治理论方法研究

Rockbursts, as a severe geological hazard, often pose a significant threat to the stability of tunnels and construction safety. Traditional circular tunnels, under non-hydrostatic pressure conditions, are prone to the formation of stress concentration zones in the surrounding rock, which can easily trigger rock bursts. In contrast, elliptical tunnels with specific axis ratios have the potential to avoid this issue, making them a focus of rock burst prevention research. This paper analyzes the stress distribution and localized tangential stress concentration characteristics in conventional circular and elliptical tunnels. Based on this context, a theoretical method for rock burst prevention using prestressed elliptical tunnels with the optimal axis ratio is proposed, and a theoretical solution for the optimal axis ratio of prestressed elliptical tunnels is provided. Using a tunnel in a high-altitude region as a case study, numerical results confirm that designing the prestressed tunnel shape according to the optimal axis ratio can completely eliminate localized tangential stress concentration, achieving an evenly distributed state, and significantly reducing the overall tangential stress level of the tunnel. Theoretically, it also offers the advantage of achieving excavation stress compensation. This provides theoretical reference for stress control and rock burst prevention in high-stress tunnel engineering.