Research on detection and treatment of loose zones in weak fracture zone tunnel

Determining the extent of tunnel loosening zones is a crucial factor in establishing reasonable support parameters. Addressing the challenge of testing tunnel loosening zones, this study focused on the Dongmachang Tunnel No. 1. Seismic wave methods are employed to test the tunnel's surrounding rock loosening zones. The results are processed using the reflection wave method, and the average wave velocity method is proposed as a standard for determining the loosening zone range. Subsequently, the surface wave method is utilized to process seismic wave data, validating the accuracy of the seismic wave method. Furthermore, a more precise range of the surrounding rock loosening zone is determined based on single hole acoustic method, and theoretical calculations. The obtained results align with the loosening zone range as determined by the average wave velocity method. Finally, a novel high-performance concrete lining structure is introduced for rehabilitating tunnel sections with significant deformations. The effectiveness of this new high-performance concrete lining structure is investigated through numerical simulations and on-site application. The study outcomes present new methodologies and technological support for determining tunnel surrounding rock loosening zones.