Numerical Response of Advance Support Structures in TBM Tunneling Through Altered Zones: A Case Study

Tunnel Boring Machines (TBMs) play a vital role in modern tunnel construction due to their efficiency and adaptability across various geological conditions. However, when tunneling through geologically altered zones, such as fault zones and soft ground, significant challenges arise, including increased wear, reduced advance rates, and heightened safety risks. This study explores advanced support measures for TBM excavation in altered zones, focusing on deformation characteristics and the bearing capacity of different support strategies in both normal and altered rock masses. Through numerical simulations on the FLAC3D platform, we compare the stress distribution and disturbance evolution in the surrounding rock with and without pre-reinforcement, as well as with single-layer and double-layer pipe-shed supports. The findings reveal that a lack of advance support leads to severe surrounding rock instability and an increased risk of TBM jamming. While single-layer pipe roofing offers partial mitigation, its limited stiffness constrains its effectiveness. In contrast, double-layer large pipe roofing provides superior bending stiffness, effectively minimizing settlement and deformation while significantly reducing the likelihood of TBM jamming. These findings offer practical guidance for the design and implementation of robust TBM support systems, enhancing tunneling safety and efficiency in complex geological conditions.