Abstract:  In this study, to reduce the risk of TBM jamming under unfavorable geologies and perform a fast jamming release, an evaluation of key technologies is performed, including geological forecast, tunneling parameters control, primary support, antijamming measures, jamming release, advance reinforcement, and ground conditioning of unfavorable geologies (such as lithologic contact zone, fault fracture zone, fullyweathered granite and siltyfine sand formation, water gushing, and highpressure waterrich weak broken altered structural belt). Moreover, the relationship between the tunneling parameters and TBM jamming is obtained, and control measures are presented. Meanwhile, certain countermeasures corresponding to different scales of unfavorable geologies, i.e. cutterhead cleaning, cyclic pipe roof, pilot tunnel, and bypass heading methods, are summarized.

Key words: railway tunnel, TBM, unfavorable geology, jamming release, pipe roof, pilot tunnel method, bypass heading