Enhancing mechanical characteristics of soft rock tunnel surrounding rock through radial yield pressure system

This study investigated the efficacy of radial yield support as an active measure to mitigate stress and deformation in deep soft rock tunnels experiencing large deformation. Traditional support methods have shown limited success in addressing this challenge. Leveraging a three-dimensional geomechanical model, this study proposes an active support system centered around radial yield pressure. This system releases stress in the surrounding rock before resisting deformation, thereby improving the mechanical properties of the tunnel and effectively controlling displacement and deformation during excavation. Through analysis using the three-dimensional geomechanical model, this study evaluated the control effect of radial yield support on surrounding rock deformation and support bearing capacity, focusing on a typical large deformation section of a highway tunnel. The results demonstrate a significant reduction in relative deformation of the surrounding rock compared to conventional support methods, with a reduction of 75.8% in tensile strain and 67.6% in compressive strain as evidenced by bolt deformation. Additionally, the contact pressure between the surrounding rock and primary support is reduced by 80%, indicating the effective control of radial yield support on plastic zone development and stress release in the surrounding rock. These findings offer valuable insights for the application of similar technologies in controlling surrounding rock in deep soft rock tunnels.