Control of Large Deformations in Jointed Surrounding Rock Induced by Plastic Flow

The large deformations of jointed surrounding rock caused by excavation poses a significant challenge in tunnel construction. This work aims to address the limitations of conventional supports, which fail to withstand the loads during large deformations induced by plastic flow, by proposing a novel combined support method of “negative Poisson’s ratio anchor cables and double-layer trusses”. With the Tabaiyi Tunnel by the small-clearance design serving as the engineering background, an analysis of the distribution and characteristics of large deformations induced by plastic flow in jointed surrounding rock is conducted. The Discrete Element Method is employed to investigate the degrees of large deformations in jointed surrounding rock under varying clearances. Furthermore, a large deformation control model for the new combined support method, based on the Finite Difference Method, was developed. The results indicate that the double-line tunnel with small clearance exacerbate large deformations induced by plastic flow in jointed surrounding rock. On-site verification confirms the effectiveness of the proposed method in ensuring the safety and stability of the tunnel, which offers a novel approach for controlling large deformations induced by plastic flow in jointed surrounding rock.