A tunnel boring machine is provided comprising a cutter head, a main beam, a first, second, and third shield; and a ground conditioning work zone within the first shield, a gripper assembly, a segment erector arm for lining the tunnel, and at least one propulsion mechanism. The ground conditioning work...http://www.google.fr/patents/US7832960?utm_source=gb-gplus-shareBrevet US7832960 - All-conditions tunnel boring machine
