Ground reaction due to tunnelling below groundwater table

摘要

Tunnelling below the groundwater table influences the hydraulic regime in the surroundingground. This will, in turn, cause seepage into the tunnel through the pores and discontinuities and often producesa long-term interaction between the tunnel and the ground. In this paper an attempt is made to identify thebehavior of surrounding ground due to seepage, and ground reaction curves (GRC) considering seepage forcesare presented for a tunnel under drainage conditions using an analytical method. It is found that the flow ofgroundwater has a significant effect on the radial displacement of a tunnel wall. While the effective overburdenpressure is reduced by the arching effect during tunnel excavation, seepage forces still remain. Therefore, thepresence of groundwater induces large radial displacement of the tunnel wall compared to dry conditions.