Abstract
Some of the important issues involved in undersea tunnels distinct from land tunnels include examining what measures should be taken against inexhaustible water and huge hydraulic pressure during construction and how to maintain the structural soundness after completion. An undersea tunnel that loses its soundness and causes flooding or any other forms of accidents while still in service is likely to put human lives at risk and pose a threat to the safety of the social infrastructure, and the restoration of such structure may become impossible in some cases. However, because much of the behaviour of tunnels under operation is still yet to be defined, the maintenance of existing undersea tunnels is practically limited to the treatment of symptoms based on past experiences, as in the case for land tunnels. Focusing on the long-term measurements of Seikan Tunnel that have been recorded since 1988, this paper organizes and analyzes their results, examines the mechanism of long-term behaviour of tunnel lining, and proposes a new soundness evaluation methodology for the undersea tunnel lining (Tuchiya, 2007).
