Abstract:

The countermeasures for tunnel water inrush are generally divided into drainage method and water sealing method; the water control experiences show that comprehensive method of drainage and water sealing is the most effective. The water sealing method depends on many conditions, i.e. acceptable water leakage conditions with large volume of water inrush and permeability coefficient of surrounding rock of larger than 10-6-10-5 cm/s, acceptable disturbance conditions induced by water level dropping and grouting conditions when reducing/avoiding water pressures on secondary lining. Grouting is the conventional method for tunnel water sealing at present. In Norway, pregrouting is adopted to control water inrush of undersea tunnels and urban tunnels; the average permeability coefficient of surrounding rock grouted is 1/100-1/25 time that of surrounding rock without grouting; the grouting holes can be reduced and the pregrouting effect can be improved by adopting high grouting pressures of 3-4 MPa. In Japan, the grouting experiences of Seikan Tunnel show that the water sealing method should be used when the permeability coefficient of surrounding rock is larger than 10-6-10-5 cm/s; the tunnel construction safety can be guaranteed and the water pressure can be ignored when the permeability coefficient of surrounding rock is smaller than 10-6 cm/s after grouting. Finally, the control technologies for water inrush of 5 typical engineering projects are introduced and the results show that effective grouting zone (antileakage structure) is very important. In fact, we still have a lot to learn.

Key words: tunnel, mining method, water sealing method, grouting, permeability coefficient, grouting pressure