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Nella giornata del 29 agosto 2003 il settore nord-orientale della regione Friuli Venezia Giulia è stato colpito da violente precipitazioni (circa 300 mm in sei ore), che hanno dato origine a numerose colate detritiche, anche di grande entità. Una di queste, avente un volume totale stimato pari a 100000 m3, ha interessato il versante in destra idrografica del fiume Fella, nell’alto bacino del Tagliamento (Rio Cucco), ed è stata oggetto di una simulazione numerica (back analysis) svolta utilizzando il codice commerciale di calcolo Flo-2D che ha permesso di individuare i valori dei parametri reologici che meglio descrivono l’evento. Il presente lavoro riporta i risultati di un’indagine sperimentale svolta su sospensioni acquose della frazione fine (passante a 63 micron) ottenuta per setacciatura da campioni prelevati nell’area interessata dal fenomeno. Lo studio ha riguardato gli effetti del contenuto di fase solida sulle proprietà shear- e tempo-dipendenti, con particolare attenzione ai parametri reologici (limite di scorrimento e viscosità plastica) che servono alla simulazione numerica del debris flow, al fine di confrontare tra loro i risultati delle prove di laboratorio e della back analysis.

This work focusses on the characterisation, by means of rheology and low field NMR, of different hydrogels obtained by photo-crosslinking of an anphyphilic polymer (polyvinylpyrrolidone). This work allows to conclude that all the studied hydrogels have a homogeneous network characterised by rather wide meshes (40 – 80 nm).

The problems connected with the use of traditional strategies (stent and coated stent) for the treatment of coronary restenosis (lumen re-occlusion due to smooth muscle cells iper-proliferation following balloon angioplasty and stent implantation) impose the development of novel solutions. Among the possible alternatives, the use of a stent embodied in a gel-polymeric film containing nucleic acid based drugs (NABDs), with antiproliferative action, seems to be promising. As gel macroscopic and structural properties are of paramount importance for the success of this approach (erosion resistance, desired release kinetics of the NABDs agent and small pressure drop), this paper is aimed to study the effect of some gel formulative variables (polymer concentration, crosslinking procedure) in order to select the best promising gel

Debris flows affect frequently the mountain regions and, because of their speed and destructive force, threaten roads, buildings and human lives. The reconstruction of debris flows paths has long been studied and several simulation models have been implemented, but a believable scenario can be obtained only by resorting to real parameters, suitable to characterize the involved material. The research presented in the paper is aimed at individuating a standard methodology that from field survey, through different laboratory analysis, comes to the assignment of numerical values to the basic parameters of the debris flow simulations (yield stress and viscosity). After obtaining these values, simulations were performed to validate the methodology. To this purpose a basin sited in the Northeast Italy has been studied and sampled. The chosen test site is located in the Val Canale valley already involved, since 2003, in at least three alluvial events. The present project started with a sampling phase. In order to ensure the representativeness of the sample, it is important to identify significant collection points, in the source, transport and depositional areas, and to collect a huge quantity of heterogeneous material. In the laboratory samples were subjected to grain-size, mineralogical and rheological analysis. Suspensions of the fine fractions were prepared at equal solids concentration and studied using a controlled stress rheometer. Different experimental methods were proved to individuate an appropriate methodology suitable to characterize the plastic behavior of the fine particle suspensions derived from the different sampling points. With the range of values obtained, numerical simulations, using FLO-2D software, were performed in order to verify the consistency of the parameters and their representativeness even if a back analysis is not available.

Le colate detritiche sono eventi frequenti in ambiente alpino dove producono effetti spesso disastrosi e manifestano dinamiche differenti in ragione dei volumi in gioco e delle caratteristiche della colata, quali concentrazione, composizione e granulometria della fase solida. Se il contenuto di solidi è elevato, le frazioni fini governano il flusso detritico che, in prima approssimazione, può essere considerato monofasico e di tipo viscoplastico. In tal caso caratterizzare il comportamento plastico di sospensioni delle frazioni fini può servire a fornire i parametri solitamente impiegati nella simulazione numerica del fenomeno, svolta con codici di calcolo basati su modelli reologici contenenti un yield stress coesivo. Il presente lavoro riguarda campioni prelevati lungo il rio Solari, situato in destra idrografica del fiume Fella in Val Canale. Sospensioni della frazione fine dei campioni prelevati in punti e profondità differenti sono state esaminate con metodi diversi al fine di caratterizzarne il comportamento plastico.

On 29th August 2003 the North Eastern part of Friuli Venezia Giulia Region was invested by an intense alluvial event. Those particularly harsh weather conditions caused more than hundred debris flow phenomena that involved the infrastructures present in the area. In this paper we analyze one single debris flow (here called Fella sx) developed on a small river located in left hydrographic of Fella River and interesting the A23 Highway with its alluvial debris. To examine the behaviour of debris flow, a back analysis study was firstly carried out with the commercial Flo-2D software so allowing to assess the rheological parameters (yield stress and viscosity) that better characterize the phenomena. Such parameters were chosen from a list of parameters available in literature. Samples were collected from the sediment source area along the flow path, sieve analyses were performed and rheological tests were carried out on the fraction finer than 0,063 mm using a rotational controlled stress rheometer (Haake RS150) equipped with the serrated parallel plate geometry (gap 1 mm). The shear-dependent behaviour was examined at different concentration ranging from 33 to 48%, by weight. Viscosity data treatment was performed in order to individuate the rheological model suitable to provide the best approximation to the debris flow behaviour. The rheological parameters derived from experimental data correlation were used to implement the Flo-2D software and the results were compared with those obtained through the back analysis simulation method.