Analisi della rottura di una condotta idrica a seguito del sisma del 26 Maggio 1991 a Potenza

The 26.5.91 Basilicata Earthquake caused the failure of one of the main waterduct of the hydraulic network of the town of Potenza. A sudden and abundant leak of water was determined by the failure. The pipes of the waterduct are made of spheroidal cast iron. Two elements of particular interest came out from the examination of the event: the low intensity of the quake and the mode of failure of the pipe. In the present paper it has been postulated that the pipe failure occurred because of the metal-metal contact in the joint caused by the deformations induced on the waterduct by the soil motion. Numerical simulation have been carried out to verify this hypothesis, where the stiffness, strength and ductility parameters have been evaluated from the laboratory tests, executed on material specimens drawn out of the broken pipe. The results of the numerical analyses have substantially confirmed the postulated hypothesis on the failure mechanism and put in evidence some useful hints for the design and construction of waterducts in seismic areas.