Abstract: During opentunnel boring machine (TBM) tunneling in complex geologies, the risks of construction period delay, cost increase, and environmental accidents are encountered easily. Accordingly, based on relevant railway tunnel quota systems and standards, some problems such as TBM jamming, hollows behind the primary support, insufficient excavation cross section, difficulty in tunnel cleaning and drainage, inaccurate spoil looseness coefficient selection, unreasonable tunneling indicators, and insufficient sewage treatment capacity encountered during TBM tunneling in Gaoligongshan tunnel are analyzed from the perspective of geology, design, and construction. Some suggestions are proposed as follows. (1) The specific requirements of the geological survey for the TBM tunnel and targeted design for TBM equipments must be improved, and the geological characteristics must be clarified. (2) According to the construction characteristics of TBM, the surrounding rock classification correction items must be optimized, reasonable reserved deformation value must be set, and adaptability of the tunnel cross section size and support parameters must be enhanced. (3) The reasonable range of the slagloosening coefficient is 1.5~1.9, and construction progress indicators of open TBM must consider the value of 14.66% in the Gaoligongshan tunnel. (4) Multiple factors must be considered for sewage treatment to protect the environment. (5) Both the standards and quota systems must be considered, and the construction must be adjusted in time to improve the matching of budget estimates with schedule and cost.

Key words: railway tunnel, open TBM, complex geologies, geological survey, standard, quota system, surrounding rock classification