ISSN : 2233-8292
One of the most important design concerns for undersea tunnels is to establish design water load and flow rate. These are greatly dependent on the hydraulic factors such as water head, cover depth, hydraulic boundary conditions. In this paper, the influence of the hydraulic design factors on the ground loading and the inflow rate was investigated using the coupled finite element method. A horse shoe-shaped tunnel constructed 30 m below sea bottom was adopted to evaluate the water head effect considering various water depth for varying hydraulic conditions and relative permeability between lining and ground. The effect of cover depth was analysed for varying cover depth with the water depth of 60 m. The results were considered in terms of pore water pressure, ground loading and flow rate. Ground loading increases with an increase in water head and cover depth without depending on hydraulic boundary conditions. This points out that in leaking tunnels an increase in water depth increases seepage force which consequently increases ground loading. Furthermore, it is identified that an increase in water head and cover depth increases the rate of inflow and a decrease in the permeability ratio reduces the rate of inflow considerably.
Atkinson, J.H., (1983) Loads on leaking and watertight tunnel linings, sewers and buried pipes due to groundwater, Technical note: Geotechnique
Curtis, D. J, (1976) The circular tunnel in elastic ground, Geotechnique
Dimitrios, K, (2005) Tunnelling and tunnel mechanics, Springer
Lee, I. M, (2002) Clogging phenomena of the residual soil-geotextile filter system, Geotechnical Testing Journal
Lee, Y.N, (1996) Cracking of subway tunnel concreteandits repair, Proc. Conf. on North American Tunnelling
Potts, D.M., (1999) Finite element analysis in geotechnical engineering, Thomas Telford
Shin, J.H., (2002) A numerical study of the effect of ground water movement on long-term tunnel behaviour, Geotechnique
Shin, J.H., (2005) The effect of pore-water pressure on NATM tunnel linings in decomposed granite soil, Canadian Geotechnical Journal
Ward, W. H., (1981) Tunneling in soft ground-general report, Proc. the 10th Intl. Conf. Soil Mechanics and Foundation Engineering