Seepage‐Induced Effective Stresses and Water Pressures around Pressure Tunnels
Publication: Journal of Geotechnical Engineering
Volume 120, Issue 1
Abstract
The change in stresses in the rock mass generated by the internal loading of a pressurized conduit, has traditionally been estimated assuming that the rock mass is impermeable and that the internal pressure in the tunnel can be treated as a mechanical load applied to the walls of the opening. The deleterious effects of pressurized seepage, percolating through the natural discontinuities in the rock mass, have generally been ignored, resulting in tunnel alignments with inadequate lateral and/or vertical cover as well as in erroneous interpretations of the in‐situ hydrojacking test results. This paper presents an approach that takes into account the effect of seepage forces by treating the fractured rock mass as a continuous porous elastic medium. The distribution of effective stresses along a radius intersecting the springline of the tunnel was estimated from closed‐form solutions derived for the simplified case of negligible circumferential seepage forces in the medium. The validity of the simplifications was assessed using the finite‐element method. The analysis presented in this report resulted in specific recommendations to establish minimum cover criteria in pressure tunnels, and also provided the basis for reevaluating the methodology currently used to determine the minimum in‐situ stress from hydrojacking test results.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Bouvard, M., and Pinto, N. (1969). “Aménagement Capivari‐Cachoeira. Étude du puits en charge.” La Houille Blanche, Paris, France, (7), 747–760 (in French).
2.
Broch, E. (1984a). “Development of unlined pressure shafts and tunnels in Norway.” Underground Space, 8(3), 177–184.
3.
Broch, E. (1984b). “Unlined high pressure tunnels in areas of complex topography.” Water Power & Dam Constr., 36(11), 21–23.
4.
Harr, M. E. (1962). Groundwater and seepage. McGraw‐Hill Book Co., Inc., New York, N.Y.
5.
Leliavsky, S. (1947). “Experiments on effective uplift area in gravity dams.” Trans., ASCE, Vol. 112, 444–487.
6.
Spencer, R. W., Laverty, B. R., and Barber, D. A. (1964). “Unlined tunnels of the southern California Edison Company.” J. Power Div., ASCE, 90(Oct.), 105–132.
7.
Schleiss, A. (1986). “Design of previous pressure tunnels.” Int. Water Power and Dam Constr., 38(5), 21–26.
8.
Terzaghi, K. (1936). “Simple tests determine hydrostatic uplift.” Engrg. News Rec. 116(25), 872–875.
9.
Timoshenko, S. P., and Goodier, J. N. (1970). Theory of elasticity, 3rd Ed., McGraw‐Hill Book Co., Inc., New York, N.Y.
Information & Authors
Information
Published In
Copyright
Copyright © 1994 American Society of Civil Engineers.
History
Received: Oct 15, 1992
Published online: Jan 1, 1994
Published in print: Jan 1994
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.