1,715 research outputs found
Studio dei meccanismi di deposizione dei Debris Flow: integrazioni tra esperienze di laboratorio, analisi di campo e modellazioni numeriche
No full textThis research is related to the study and modelling of the depositional processes of debris flows and an understanding of the related rheological behaviour. The main aims of this study are to analyse the depositional features of a debris flow, to verify the possible contribution of laboratory tests, carried out by means of a tilting-plane rheometer, to determine the rheological parameters and to investigate the reliability and limitations of computer models employed for debris flow simulation and rheological parameter determination.
The laboratory tests were been carried out at the Institute for Hydrological and Geological Protection of the Italian National Research Council (CNR IRPI) in Padova. The physical model consists of a 2 x 1 m tilting plane with inclination from 0° to 38°, on which a steel tank with a removable gate has been installed. A fixed horizontal plane (1.5 x 1 m), with an artificial roughness to simulate natural basal friction, served as the deposition area. In total, 93 laboratory tests were carried out: 62 tests simulated the quasi-static formation of a fan (with the tank installed at the lower end of the tilting plane), the remaining 31 examined dynamic fan formation by the means of a flume. The steel tank, with a removable gate facing the deposition plane, is parallelepiped with a square base (15 x 15 cm and 33 cm high) having a maximum volume of 7 dm3. The laboratory tests were conducted using three different materials: plastic cylinders with a diameter and height of 3 mm; medium to fine gravel; and debris-flow matrix (with a diameter < 19 mm), varying amounts of water were added to the debris-flow matrix to test solid concentrations in a range between 0.45 and 0.67. Data analysis included the development of semi-empirical equations for runout distance, the maximum width of the deposit and total travel distance. An energy balance approach was tested in order to determinate the rheological parameters of the debris-flow matrix, this method is based on the comparison between the potential energy of the mass stored in the tank and the work made in the process of deposit formation.
The field sites related to the debris-flow events are located upstream of the town of Cortina d'Ampezzo (Fiames locality, Belluno, Italy), where an intense rainstorm triggered six debris flows during the afternoon of 5th July 2006. Immediately following the event, field surveys were carried out in the study area. These field surveys made it possible to measure several features, including the debris-flow deposits, main channels and initiation areas. Samples taken from the debris-flow deposits have been used for laboratory tests. Total travel distances and the runout distance on fans measured in the field were compared with formulas found in the literature (empirical/statistical and physically oriented) and also compared to the results of the laboratory tests. An estimation of shear stress from the field site was calculated using Johnson's (1970) formula.
The Fiames debris-flow event of 5th July 2006 and the laboratory tests (dynamic runs) were simulated using FLO-2D, while RAMMS (Rapid Mass MovementS) was used solely to simulate the Fiames event. FLO-2D (O'Brien, 2003) is a two-dimensional flood routing model with a rigid bed (debris-flow simulations) or a mobile bed (sediment transport simulations), it simulates water flows in wide rivers as well as non-Newtonian flows over alluvial fans. FLO-2D numerically routes a flood hydrograph while predicting the area of inundation, the maximum depth and the flow velocity in each cell of the square grid system derived from input topographic data. RAMMS was developed in 2005 by the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf and the Swiss Federal Institute for Snow and Avalanche Research (SLF), Davos. RAMMS uses a one-phase approach based on Voellmy rheology (Voellmy, 1955; Salm et al. 1990). The input file combines the total volume of the debris flow located in a release area with a mean depth. The model predicts the area of inundation, the maximum depth and the flow velocity in each triangular-shape cell of the input DTM.
The limitations of the numerical simulations relating to the laboratory tests were investigated to verify to what extent rheological parameters could be determined using this indirect method. The analysis of the Fiames event enabled understanding of the rheological behaviour related to the dolomitic debris-flows and the influence exerted by the input parameters on the final results. Finally, some improvements to the RAMMS model were proposed to obtain simulations in keeping with the events observed in the field
Ricostruzione delle portate di piena mediante indicatori di campo: analisi comparata di alcuni torrenti della provincia di Belluno
No full textLa ricostruzione delle portate di piena per mezzo delle tracce lasciate dall’evento ha assunto notevole importanza negli ultimi anni a causa del ripetersi di eventi alluvionali estremi. Si è accresciuta di conseguenza la richiesta di una maggiore comprensione dei fenomeni e di una stima quantitativa degli eventi occorsi, al fine di progettare e gestire interventi sia conservativi che di prevenzione. L’obiettivo del presente lavoro è di testare l’affidabilità di alcuni metodi di stima paleoidrologica in alcuni tratti di torrenti montani. Gli indicatori di campo utilizzati sono le tracce lasciate sulle sponde, il diametro intermedio dei massi più grossi depositati dalla piena, la geometria delle buche di scavo e la lunghezza d’onda degli step della morfologia a gradinata. E’ stata condotta una campagna di rilievi su cinque tratti di corsi d’acqua montani della Provincia di Belluno: i torrenti Cordevole e Boite ed il fiume Piave. I dati sono stati elaborati applicando le seguenti metodologie di stima: il metodo slope-area, l’ipotesi di criticità della corrente, il metodo dei diametri competenti, i parametri di scavo, la geometria delle forme di fondo e le condizioni di moto in regime di forte scabrezza. Mediante un confronto tra i picchi di piena stimati e quelli misurati dalle stazioni idrometriche regionali, si è concluso che i valori stimati sono ragionevoli e si collocano tra l’ordine di grandezza ed il dato puntuale
Reologia e distanza di arresto dei debris flow: sperimentazioni su modello fisico a piccola scala
No full textLo studio di campo delle caratteristiche di movimento delle colate fangose e fangoso-detritiche
(debris flow) presenta delle notevoli difficoltà tecniche e operative a causa dell’imprevedibilità temporale del fenomeno, della sua breve durata e dell’elevata forza
distruttiva del flusso. Per questa ragione l’uso di modelli fisici a scala ridotta può considerarsi un valido strumento di indagine per l’analisi reologica dei debris flow o
quanto meno della loro componente medio-fine (ghiaie, sabbie, limi, argille), che ne condiziona fortemente gli sforzi deformativi di tipo viscoso, frizionale e collisionale. In questo ambito si sono svolte alcune prove sperimentali mediante un reometro a piano inclinato, costituito da una canaletta, lunga 2 m, seguita da un piano orizzontale che
funge da zona di deposizione. La canaletta è dotata di un serbatoio per il carico delle miscele fangoso-granulari, dal quale vengono poi rilasciati impulsivamente, a mezzo di
una paratoia, flussi a concentrazione volumetrica nota. Sono state testate alcune miscele costituite da sedimenti campionati da recenti depositi di colata: due campioni
(uno indisturbato ed uno rimaneggiato) provengono da un debris flow verificatosi in zona Dolomitica (falde del massiccio del Pomagagnòn, Cortina d’Ampezzo, Belluno) e
sono caratterizzati da diverse percentuali dei sedimenti coesivi, un terzo campione è composto da materiale prevalentemente sabbioso prelevato dalla colata del rio
Gabbiolo (affluente del torrente Sarca di Val Genova, Trento), un ultimo campione (rio Val degli Schivi, Trento) presenta un discreto assortimento di sedimenti a grana grossa e a grana fine. Le prove sperimentali hanno portato a determinare delle relazioni piuttosto strette tra la pendenza media di attrito dei vari flussi gravitativi e la loro
concentrazione volumetrica, mettendo in luce come la composizione granulometrica dei sedimenti ne influenzi grandemente la mobilità. Le sperimentazioni hanno inoltre
suggerito un metodo per la stima della distanza di arresto, che è stato verificato mediante il confronto con eventi reali
Basal shear stress of debris flow in the runout phase
No full textA laboratory device is proposed to assess the basal shear stresses generated by debris-flow
mixtures during their runout phase. The device consists of an inclinable box with a gate facing a deposition
plane. The box is filled with a selected debris-flow mixture, and after sudden opening of the gate, the
features of the dam-break deposit can be measured. Based on some simplified assumptions of the energy
balance, a methodology is proposed to assess basal shear stresses. The device has been tested using sediment
samples from debris-flow deposits generated by two catchments of the Dolomites (Cortina d'Ampezzo,
Belluno, Italy) by carrying out runout tests for different sediment concentrations by volume. The results
show how the static Coulomb friction law is valid in the runout phase, with friction angles on the order of the
angle of repose of the same material in dry conditions. The data elaboration also yields an innovative
constitutive equation for shear stresses. This relation merges the Coulomb mixture approach with the concept
of a one-phase flow with a certain rheology. This integration offers a useful insight into the weaknesses of
the rheological approach if it is not properly scaled up to the ambient pressure of interest
Comparison between FLO-2D and RAMMS in debris-flow modelling: a case study in the Dolomites
No full textThis paper presents a comparison of the results obtained through the use of two numerical models for debris flow simulation. FLO-2D and RAMMS were used to carry out a back analysis of a well documented debris-flow event, which occurred on July 2006 in the Dolomites (Fiames locality, Belluno, Italy). The performances of FLO-2D and RAMMS are tested in terms of adaptation degree to the observed field data
TUTELA DEL LAVORO E LIBERTA' D'IMPRESA NEI PROCESSI DI ESTERNALIZZAZIONE
No full textL’elaborato analizza le conseguenze lavoristiche della successione fra imprenditori, muovendo da una ricognizione delle varie tipologie di esternalizzazione con le relative esigenze e principali criticità.
L’indagine si concentra in primo luogo sul trasferimento d’azienda, esaminando la normativa e la giurisprudenza europee per passare poi alla disciplina di diritto interno, alle procedure sindacali e a uno specifico focus sul trasferimento delle aziende in crisi.
Successivamente l’autore si sofferma sull’appalto, prendendone in particolare considerazione gli indici di genuinità, i criteri di distinzione dalla somministrazione illecita di manodopera e la tutela delle maestranze in caso di avvicendamento fra imprese.
Da ultimo, la ricerca approfondisce le c.d. “clausole sociali”, sia di prima che di seconda generazione, valutandone la compatibilità con il diritto eurounitario e con la costituzione nonché riflettendo sui possibili rimedi in caso di loro violazione.The author analyzes the labour consequences of the succession between entrepreneurs, starting from a recognition of the various types of outsourcing with the related needs and main critical issues.
The survey focuses primarily on the transfer of businesses, examining European legislation and case-law and then moving on to internal legislation, trade union procedures and a specific focus on the transfer of companies in crisis.
The author then dwells on the contract, taking into account in particular the indications of authenticity, the criteria of distinction from the illicit administration of labour and the protection of workers in the event of turnover between companies.
Finally, the research deepens the "social clauses", both first and second generation, assessing their compatibility with European law and with the constitution and reflecting on possible remedies in case of their violation
Ultra Low Carbon Vehicles: New Parameters for Automotive Design
No full textAs the influence of vehicle emissions on our environment has become better understood, the UK government has recently placed urgent emphasis on the implementation of low carbon
technologies in the automotive industry through: the UK Low Carbon Industrial Strategy. The overall objective is to offer big incentives to consumers and support for the development of infrastructure and engineering solutions. This scheme however does not consider how the development of functional and experiential user value might drive consumer demand, contributing to the adoption of low carbon vehicles (LCVs) in the mass market.
With the emergence of the North East of England as the UK’s first specialised region for the development of ultra-low carbon vehicles (ULCVs), ONE North East, as a development agency for the region's economic and business development, and Northumbria University Ideas-lab have supported a project to facilitate innovation through the collaboration of technology, research and development (R&D) and business. The High Value Low Carbon (HVLC) project aims to envisage
new user value made possible by the integration of low carbon vehicle platforms with new process and network technologies. The HVLC consortium represents vehicle manufacturers and their suppliers as well as technology based companies and through an ongoing process of design concept generation the project offers a hub for innovation led enterprise.
Whilst new technological developments in areas such as power generation, nano materials, hydrogen fuel cells, printed electronics and networked communications will all impact on future automotive design, the mass adoption of low carbon technologies represents a paradigm shift for the motorist. This paper aims to describe how the mapping of new parameters will lead to new transport scenarios that will create the space for new collaborative research on user experiences supported by innovative technologies and related services
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Matteo Maria Boiardo (1441-1494)
No full textMatteo Maria Boiardo – contemporary of Sir Thomas Malory and forerunner of Shakespeare, Spenser, Milton, Cervantes, Tolkien, and C.S. Lewis – is best known as the author of the Orlando Innamorato [Orlando in Love], a poem in ottava rima organically merging Carolingian epic and Arthurian romance. He was also a lyric and pastoral poet, playwright, and translator of classical texts into the Italian vernacular. Matteo was active in Italy during the years of 1463 throughout 1494, the year of his death
Uno sguardo all'Est. Lavoro e diritti fondamentali in Russia e negli altri Paesi della Comunità di Stati indipendenti
No full textNel contributo l'autore, dopo aver esaminato i diritti fondamentali del lavoro presenti nelle Costituzioni dei Paesi della Comunità di Stati indipendenti, si sofferma sul diritto del lavoro russo. La trattazione, a carattere diacronico, abbraccia i rami principali del diritto del lavoro: il rapporto individuale, le relazioni collettive, il mercato del lavoro. L'autore rileva una sorprendente continuità nelle linee essenziali del diritto del lavoro russo, pur nel susseguirsi di sistemi socioeconomici completamente diversi. Egli conclude che il diritto del lavoro russo appartiene saldamente alla matrice europea della materia.The contribution of the author starts by examining fundamental labour rights recognised by the Constitutions of the Countries of the Community of Independent States. Then the author focuses upon Russian Labour Law, going through the history of the main branches of the discipline: the individual relationship, industrial relations, the labour market. The article finds a surprising continuity in the essential lines of Russian Labour Law, in spite of the completely different socio-economic systems that were experimented in Russia during the twentieth century. The author concludes that Russian Labour Law clearly belongs to the European matrix of the discipline
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