44 A case history about the application of pre-reinforcement in the excavation of tunnel portals in weathered rock
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Published:1984
A. Palmieri, 1984. "44 A case history about the application of pre-reinforcement in the excavation of tunnel portals in weathered rock", Design and Performance of Underground Excavations: ISRM Symposium — Cambridge, U.K., 3–6 September 1984, E. T. Brown, J. A. Hudson
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Geotechnical problems encountered during the execution of three tunnel portals for the Bumbuna Falls Hydroelectric Project (Sierra Leone) are described. Rock types are granite and amphibolite with different degrees of tropical weathering. The use of geostructural surveys and kinematic analyses to recognise potential failure mechanisms and the application of the Ground-Support Interaction (GSI) model to the design of pre-supports are described. Some conclusions are drawn from the GSI application, about the effect of spiling in increasing the stand-up time of the portal roof under critical ground conditions.
GENERAL
GEOTECHNICAL ASPECTS OF THE WORKS
RIGHT AND LEFT INLET PORTALS
RIGHT TUNNEL OUTLET PORTAL
CONCLUSIONS
ACKNOWLEDGEMENTS
REFERENCES
