Abstract: Addressing the challenging problem of frequent full-face rock tunnel boring machine (TBM) jamming in adverse geological sections, which severely restricts construction efficiency, the authors, based on mechanical analysis and construction practices of typical engineering cases, propose two types of jamming: stress-induced jamming (arising from the convergence and extrusion of surrounding rock under high ground stress) and gravity-induced jamming (resulting from the collapse of fractured surrounding rock). The authors clarify the essential prevention and control points for both and establish a three-level jamming risk classification system (low, medium, and high). For stress-induced jamming, proposed technical measures include insitu ground stress release, TBM over excavation, and primary flexible support; while for gravity-induced jamming, technical strategies are proposed, including advance reinforcement, synchronous protection during over-excavation, and an overall impact resistance design for the TBM. Furthermore, new machine types have been innovatively developed, such as the dual-structure TBM, the boring and blasting machine integrating drilling-blasting and tunneling, and the parent-child TBM for step-by-step excavation. These solutions collectively improve the adaptability and safety of TBMs in complex geological conditions. The abovementioned technologies are proven to effectively reduce the jamming risk of TBMs and improve construction efficiency, with some already successfully applied in typical projects such as the Gaoligongshan tunnel. There, they effectively addressed challenges of large deformation in soft rocks and fault fracture zones, thereby providing a systematic and valuable engineering solution for safe and efficient TBM tunneling in adverse geological conditions.

Key words: TBM, stress-induced jamming, gravity-induced jamming, TBM over-excavation, advance reinforcement, synchronous protection, dual-structure TBM