Seismic analysis of the high arch concrete dam of the water power plant "Piva"

Abstract

Original scientific paper This paper analyses the seismic strength of the high arch concrete dam of the Hydro-power plant "Piva" on the river Piva in Montenegro, which was built in the seismic active area almost forty years ago. This is the double curve concrete arch dam, 220 m high and it belongs to the group of very high dams, among the highest 25 in the world. Linear and nonlinear analysis was performed. These analyses are very complex because they should include simultaneous interaction of system dam-foundation-reservoir. Calculation model was prepared using 3D finite elements for linear and nonlinear seismic analysis. Normal stresses and displacements which are obtained by the linear and non-linear analysis are different by the values and distribution along the dam body. Stresses obtained by the non-linear analysis are significantly less than the stresses obtained by the linear analysis, but when the displacement is about there is inverse case. Linear analysis gives the satisfying results for lower levels of the dam stress. When the tension strength is exceeded in the joints among the blocks, the dam goes into non-linear state of behaviour and in that case non-linear analysis should be used. Keywords: arch dam; dam-foundation-reservoir system; seismic analysis Seizmička analiza visoko lučne betonske brane hidroelektrane "Piva"Izvorni znanstveni članak U radu se analizira seizmička otpornost visoko lučne betonske brane hidroelektrane "Piva" na rijeci Pivi u Crnoj Gori, izgrađenoj prije gotovo četrdeset godina u seizmički aktivnom području. To je betonska lučna brana s dva luka, 220 m visoka i spada u grupu vrlo visokih brana, među 25 najviših na svijetu. Provedena je linearna i nelinearna analiza. Te su analize vrlo složene jer bi trebale uključiti simultanu interakciju sustava brana-temelj-rezervoar. Proračunski je model pripremljen uz primjenu 3D konačnih elemenata za linearnu i ne-linearnu seizmičku analizu. Normalna naprezanja i pomaci dobiveni linearnom i ne-linearnom analizom su različitih vrijednosti i raspodjele duž tijela brane. Naprezanja dobivena ne-linearnom analizom znatno su manja od naprezanja dobivenih linearnom analizom, ali kada se radi o pomacima, slučaj je obrnut. Linearnom se analizom postižu zadovoljavajući rezultati kod nižih stupnjeva naprezanja brane. Kod prekomjerne vlačne ćvrstoće u spojevima između blokova, brana prelazi u ne-linearno stanje ponašanja i u tom je slučaju potrebno primijeniti ne-linearnu analizu.