Indagine sperimentale sull'evoluzione morfologica di un alveo fluviale soggetto a restringimento

ABSTRACT On occasion of recent alluvial events of considerable entity, lots of road and railway bridges over the rivers have been largely damaged or destroyed pointing and the need to improve the calculation and valuation methods of vulnerability of such (handmade articles). The topicality of the interest for this subject is proved by different programmes today’s research promoted by State authorities, Societies an agencies of management both national an international. The problem is will known also because, sometimes, it unhappy gained the news thanks to some tragedies resulting from the undermining of the piers or the abutments of the bridges. In Basilicata, too, there are bridges in disastrous conditions, because of the undermining of foundations and the consequent widening of surface impact that extends the local effects. The aim of this work is to give a contribution to research, analysis and comprehension of the phenomenon of general and local erosion of river bend paying attention to the effects caused from the contraction of the transversal section. The scientific and technical literature reports a lot of studies, both on theory and application, about the reasons and mechanics of hydraulic phenomenon that cause the damage, but in effects it is not exhaustive. The phenomenon has been more intensely studied only from the second half of the last century but with different difficulties: on the hand there’s a lack of data supplied by researches related to studies in that field, on the other hand there is a divergence in the final valuations about the same phenomenon. This divergence can depend on the high number of existing variables, even in the simpler problem. So, it is necessary to simplify the conditions trough which we can analyse the phenomenon.