A new design for a large cavern in the Alps

Abstract

The Pont-Ventoux underground Power Plant is a 150 MW hydroelectric project in the North-West part of the italian Alps. During the geological survey, necessary for the definition of the mechanical parameters, it was found that the original project location was unsuitable due to a fault zone. The power station complex was therefore relocated to a new area with better mechanical conditions. As a result the project of the cavern was modified and a new shape created. The project engineers designed three-dimensional egg-shaped cavern with two abses on both ends of the cavern and an elliptical plan well. To study and research such an innovative shape several numerical analysis were carried out. An hybrid approach F.E.M.-B.E.M. (finite elements method-boundary elements method) was used. The results obtained from these numerical analysis confirmed the validity of the whole idea. The new cavern is therefore supported mainly by means of untensioned grouted dowels and shotcrete.