Study on the evolution of surrounding rock stability during non-blasting construction of tunnels in weak rock mass

The drilling and blasting method exerts a considerable impact on the surrounding rock, causing significant disturbance and vibration, which poses severe stability challenges in weak rock tunnels. To quantitatively evaluate the stability evolution under non-explosive construction compared to traditional methods, this study takes the New Shangjiagou Tunnel of the Xi’an–Yan’an High-speed Railway as a case study. Numerical simulations using LS-DYNA (for blasting dynamics) and FLAC3D (for excavation response) were combined with on-site acoustic wave measurements and deformation monitoring. The results indicate that the non-explosive construction method using a Boom-type tunnel roadheader offers superior stability. Specifically, it reduces the maximum deformation by 5.7 mm (27%) and the plastic zone area by 30% compared to the drilling and blasting method. Furthermore, the roadheader excavation induces a more uniform plastic zone distribution, whereas blasting increases the damage depth to the surrounding rock by approximately 0.5 to 0.7 m. The vertical deformation during roadheader excavation is primarily concentrated in the initial stage, followed by rapid stabilisation. These findings confirm that the Boom-type roadheader is a viable and superior alternative for tunnel construction in weak rock masses, providing a theoretical basis for optimising excavation methods in complex environments.