4. Description of TBM methods

Tunnel boring machines (TBMs) can be defined as the set of machines and equipment that perform virtually the entire process of mechanized tunnel construction. The ground is cut in full cross-section by a rotating head, so the cross-section is almost invariably circular, except in rare cases where the head is equipped with multiple wheels to create tunnels with non-circular cross-sections. While traditional tunnelling methods are a continuation of ancestral mining techniques, tunnel boring machines (TBMs) are the fruit of an industry that has taken advantage of robotization and automation to enable tunnelling in increasingly sensitive geotechnical and environmental contexts, while guaranteeing the safety of workers.

Genuine mobile underground factories, TBMs successively or simultaneously perform functions as diverse as cutting the ground, stabilizing the walls of...