PDF - 9Mo - Grande Dixence SA

GD. P.21Typesof damGravity damGrande Dixence is a typical gravity dam. It is essentiallya triangular body with an extremely broad basewhich gets narrower towards the top. Its own weight(15 million tonnes in the case of Grande Dixence) isenough to resist the water pressure.There is also a variation of this design: the gravity-archdam. This type of storage dam gets its stability bothfrom its own weight and from the transferral of the waterpressure to the valley sides (e.g. Schlundbach damin Lucerne Canton).Gravity damArch damIn contrast to the gravity dam, which is often a massivelyheavy construction, the concrete arch dam is particularlyelegant. But the decision to build this type ofdam depends on many factors: the shape of the valley,the lie of the land, the materials locally available …The arch dam’s main characteristic is clean lines givingan impression of lightness. Rather than fighting theweight of the water head on, the arch transfers boththe vertical and horizontal stresses to the valley sides.The Z’Mutt dam, at the foot of the Matterhorn is a perfectexample.Arch damEmbankment damThe principle of the embankment dam is straightforward- a certain amount of material is gathered togetherin order to hold back the water. Generally, at the centreof the dam there is a completely watertight core.It is reinforced both upstream and downstream bybackfilling and piles of rock.In contrast to the other types of concrete dam, the embankmentdam has a cross-section that is much widerthan it is high (e.g. Mattmark dam in Valais Canton).Embankment dam