ABSTRACT:

The general and structural geology, as mapped in the field, and confirmed by drillings and underground follow-up mapping, play a large role for the excavation and support design of rock engineering structures, such as underground tunnels and caverns as well as open slopes. A number of failure cases are described. Also a number of successful cases are described where the experience gained from failures was used to design and carry out reconnaissance study, site investigations, geological follow-up, and support systems. The conclusion is, a. o. that it is essential to have a full understanding of the general structural geology of an area in order to carry out successful design and excavation of an engineering structure. This can be applied not only to poor rock, but also to hard rock of a good quality with discontinuous structures, which are adverse with respect to their mineralogy, size and orientation in relation to the tunnel, cavern or slope.

RESUME:

La geologie generale et structuale telle qu'elle est observee, cartographiee sur le terrain et confirmee par des forages ou galeries de reconnaissance, joue un rôle important dans l'excavation et le design des structures telles que les tunnels souterrains, les cavernes et les talus ouverts, dans des massifs rocheux de bonne qualite. Un certain nombre de cas d'echecs sont decrits. L'experience des cas reussis est utilisee dans la planification et la realisation des etudes de reconnaissance, de prospection de sites, de suivi de la geologie et des systèmes de support. En conclusion, on peut dire qu'il est essentiel d'avoir une comprehension complète de la geologie generale et structurale d'une zone donnee afin de concevoir une un ouvrage dans un massif rocheux de bonne qualite. Mais, les structures discontinues sont opposees aux premières par leur mineralogie, dimension et orientation en relation avec un tunnel, une caverne ou un talus.

ZUSAMMENFABUNG:

Struktur- und allgemeine Geologie, wie im Felde kartographisch aufgenommen, und von Bohrungen bestatigt sind, spielen eine groβe Rolle, auch im Bergbau in Gesteine von guter Qualitat, sowohl unterirdische tunneln aIs Böschungen. Einige Beispiele von Rutschungen sind hier beschreibt. Auβerdem einige geglueckten Faile sind beschreibt, wo die Erfahrungen von die Rutschungen fuer Entwurf und Ausfuehrung von Erkundung, Kontrolle und Ausbau benutzt warren. Der schluβsatz ist daβ es ist notwendig die strukturgeologie zu verstehen fuer die ausfuehrung der Konstruktion und des Bau in Gestein von gutes qualitat, aber mit strukturen, die gefahrlich sind, mit Ruecksicht auf Mineralogie, Gröβe und Richtung.

GENERAL

Hydroelectric tunnelling is a substantial part of Swedish rock engineering. In the North, the topography is characterized by the Caledonian mountain chain which is located in the West, along the Swedish-Norwegian border, with the woodlands sloping gently from the toe of the mountainous areas to the sea, resulting in long run-off stretches. These conditions have made it necessary to design a large number of power stations, relatively low heads, 5–100 m (IVA 1981) along each river. This is in contrast to the situation in Norway where there are few stations with high heads (up to 1000 m) along the relatively short rivers,. The Swedish hydropower stations are characterized by long headrace or tailrace tunnels, with large cross sectional areas. At present the total length of existing hydro tunnels in Sweden with an area exceeding 50 sq m can be summarized as follows (Manna & Hansen 1987).

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