INFLUENCE OF SITE GEOLOGY ON THE SEISMIC BEHAVIOR OF CONCRETE DAMS

Abstract

In seismic zones, arch dames are the most feasible when the geology and the integration of
ancillary structures allow it. Arch dams postpone the hydrostatic push on the foundation by bows (under
compression). It is the slenderness of the valley, the geometry of the arch, and the contrast of rigidity
between the concrete and the rock that determine the behavior of the structure. The stability of this type of
dam differs essentially from that of gravity dams, which results from a certain inequality between the flow of
water and the weight. An intermediate design combination between the two; gravity and arch profiles is the
arch-gravity dam, which takes advantages of each type of dam. The failure of this type of structure under
earthquakes is generally accompanied by dramatic damage on both human and material sides. Consequently,
it is important to study in a reliable and precise way their dynamic behavior considering the impact of the
geology of the site, which plays an important role on the profile to be adapted and on the seismic response of
the structure. The purpose of this paper is to carry out a comparative analysis between the gravity dam
response and the single and double curvature arch dam response with variable site conditions. A finite
element numerical modeling using the Cast3M code is performed to analyze and evaluate the vulnerability of
each profile design. Proportionality is deduced between the displacement of the crest and the rock type on the
one hand, and between the crack opening evolution and the rock deformation modulus, on the other hand.