Abstract: Application of the drill-and-blast method generally leads to deterioration of rock properties in a disturbance-damaged region of rock tunnels. In this study, different mechanical models of disturbance-damaged rock tunnels were introduced according to the elastic-plastic states of both disturbance damaged rock and non-disturbance rock. Brittle-plastic solutions of stress, displacement, and plastic zone radius in disturbance-damaged rock tunnels were then presented by adopting the unified strength theory, the elastic-brittle-plastic model, and a non-associated flow rule. Furthermore, the study discussed the conversion paths and determinative approaches of the tunnel mechanical model and compared the results with those in the literature. Influences of various factors were analyzed, demonstrating that the obtained brittle-plastic solution of rock tunnels accounts reasonably for comprehensive effects of intermediate principal stress, tunnel disturbance range, rock post-peak strength, and dilatancy. Additionally, the solutions can be reduced to many traditional ones through combined parameter transformation, and its verification is demonstrated. As a result, it has important theoretical significance and application prospect. The determination of tunnel mechanical model is closely related to intermediate principal stress and rock disturbance range, which significantly affects distributions of tunnel stress and displacement as well as ground reaction curve. Support pressure and tunnel stable deformation increase obviously with the decrease of rock post-peak strength and the increase of dilatancy parameters.

Key words: disturbance damaged rock, unified strength theory, elastic-brittle-plastic model, dilatancy, ground reaction curve