Abstract: A case study on the pilot tunnel of the Daliangshan No. 1 tunnel is conducted with the aim of enhancing the anti-jamming and jam-releasing capabilities of remanufactured open tunnel boring machines (TBMs) in soft rock tunnels. The necessity of anti-jamming transformations for remanufactured TBMs is analyzed by employing suitable engineering practices, and transformation strategies targeting the main drive, support system, and cutterhead over-excavation system are proposed. The engineering practices demonstrate the following. (1) Replacing the main drive gearbox reducer increases the remanufactured TBM′s rated and recovery torque by 38%. (2) Modifications to the shield and pipe-roof drilling machine facilitate the rapid installation of advance pipe roofs using shield guide holes. In addition, an integrated gear ring facilitates the quick mobility and precise positioning of the pipe-roof drilling machine and emergency shotcrete equipment. These measures result in the establishment of a continuous and enclosed support system that integrates the shield, rock bolts, steel ribs, emergency shotcrete, and steel arches. (3) An over-excavation scheme incorporating cutter edge extension and pre-reserved over-excavation cutter boxes is proposed. Combined with main drive elevation technology, this approach facilitates long-distance continuous over-excavation in soft rock tunnel sections. Finally, field applications confirm the feasibility and effectiveness of the proposed anti-jamming transformation strategies.

Key words: open tunnel boring machine, remanufacturing, anti-jamming, structural transformation, soft rock, highway tunnel