Abstract: It is necessary to find a quantitative theoretical basis for selecting a watercontrol scheme for the exploration of vertical tunnel shafts. Based on the qualitative selection characteristics of construction schemes for vertical shafts, the data measured after 2 examples of ground pregrouting, 42 examples of workingface grouting, and 47 examples of grouting behind the lining during the construction of two vertical shafts in the Gaoligongshan tunnel are analyzed. The watersealing efficiencies for these three grouting methods are calculated by statistically analyzing the residual water leakage in the shaft after grouting. Finally, based on data mining with a specific decisionmaking method, the mathematical expectation for the watersealing efficiency after using one or multiple grouting methods is obtained, and a quantitative evaluation index for watersealing of a vertical shaft in granite that meets this mathematical expectation is proposed. The calculations show that the watercontrol capacity of the combined grouting scheme is 12～15 times higher than that of the singlegrouting scheme. This suggests that systematic watersealing measures should be taken before shaft construction or excavation in granite to improve the safety of the shaft and the construction environment.

Key words: railway tunnel, vertical shaft, water seal scheme, water control efficiency, grouting