Determination Minimum Value of Face Support Pressure for Underwater Tunneling with Complex Condition

Abstract

Underground water is a big problem for tunneling under rivers or oceans. So it’s practical method to consider pore pressure for determination minimum value of surface support pressure. What’s more, the earth thickness above excavation tunnel changes because of the riverbed existence, which makes surface support pressure more difficult to set. Active earth pressure theory, Murayama formula and fluid-structure interaction theory are used to analysis the minimum value of surface support pressure. Relationship between support pressure and horizontal displacement, which is supporting characteristic curve, is established. The determination principle for minimum value of surface support pressure is comprehensive analysis of plastic zone development and the level of face horizontal displacement. The results suggest that: the active earth pressure can be used as the lower limit for surface support pressure set in horizontal excavation section; but it can’t meet the requirements for the uphill section of notching section. But minimum value of surface support pressure for the slurry can be determined by supporting characteristic curve.