Dipartimento di Ingegneria Civile - Tesi di Dottorato

Permanent URI for this collectionhttps://lisa.unical.it/handle/10955/99

Questa collezione raccoglie le Tesi di Dottorato Dipartimento di Ingegneria Civile dell'Università della Calabria.

Browse

Author: search.filters.author.Furgiuele, Franco

Search Results

Now showing 1 - 10 of 17
  • No Thumbnail Available
    Item
    New on-line model for shoreline evolution at beaches composed of not cohesive grains of any size
    (Università della Calabria, 2020-02-12) Francone, Antonio; Furgiuele, Franco; Tomasicchio, Giuseppe Roberto; Frega, Ferdinando
    Over recent decades, efforts have been made to find robust methods for predicting shoreline evolution near to the coastal structures. This requires a rigorous understanding of the key coastal processes that drive sediment transport, and how they are impacted by the presence of structures. Once this understanding is reached, a method for predicting morphological shoreline evolution is required. In this context, numerical modelling plays an important role. A new one-line model for shoreline evolution at beaches composed of not cohesive grains of any size is proposed: the General Shoreline beach (GSb). GSb model is based on the one-line theory, for which it is assumed that the equilibrium beach profile remains unchanged (Dean, 1990), thereby allowing beach change to be described uniquely in terms of the shoreline position. The longshore sediment transport rate is estimated by means of a general formula/procedure (Tomasicchio et al., 1994; Lamberti and Tomasicchio, 1997; Tomasicchio et al., 2013; Tomasicchio et al., 2015) combining an energy flux approach with an empirical/statistical relationship between the waveinduced forcing and the number of moving units. The uniqueness of the proposed new one-line model consists in the possibility to simulate beach change, including the effects of coastal structures (i.e. groynes, detached breakwaters), at a mound composed of not cohesive grains of any size, from sand to rock units. Despite other existing models, the GSb model presents a calibration factor, KGSb solely and it has been calibrated and verified against field and laboratory data on sandy and mixed beach (sand and gravel) referring to simple groyne and detached breakwater (Ming and Chiew, 2000; Hamilton et al., 2001; Martin-Grandes et al., 2009; Medellin et al., 2018;). Optimal values of KGSb, valid for different types of not cohesive grains and coastal structures, have been reported. It is showed that the GSb model can be considered a reliable engineering tool to conduct morphodynamics studies. A demo version of the GSb model, for Mac and Windows systems, has been released for the scientific community and is available at www.scacr.eu.
  • Thumbnail Image
    Item
    A Comprehensive analysis of hydrological benefits of low impact development techniques: experimental investigation and numerical modeling
    (Università della Calabria, 2020-03-05) Palermo, Stefania Anna; Furgiuele, Franco; Piro, Patrizia
    Urban floods, recently increasing due to the combine effect of climate change and urbanization, represent a potential risk to human life, economic assets and environment. In this context, the traditional urban drainage techniques seem to be inadequate for the purpose, therefore a transition towards an innovative sustainable and resilient urban stormwater management is a valid solution. One promising strategy is the implementation of decentralized stormwater controls, also known as Low Impact Development (LID) systems that provide several benefits at multiple scales. Despite several studies demonstrated the LIDs’ capability in terms of surface runoff reduction, the transition towards a sustainable urban drainage system, which includes these techniques, seems to be very slow. One of the key scientific limiting factors can be found in the lack of comprehensive analyses able to highlight the hydrological performance and the physical processes involved in LID systems at multiple spatial scale and by considering long-term experimental data. The complexity of the physical processes, involved in each specific LIDs stratigraphy, requires modeling tools able to accurately interpret their hydraulic behaviour, as well as to correlate their hydrologic efficiency with the management of stormwater in the surrounding urban area. For these reasons, so far different empirical, conceptual and mechanistic models have been proposed, however in many of these studies, the hydrological parameters, as well as the physical ones were not properly investigated, limiting the analysis only to specific factors, or by considering literature values for the numerical modeling. Thus, principal aim of this thesis is to present a comprehensive analysis of the hydrological benefits of LID techniques by experimental investigation and numerical modeling. To achieve this goal, several analyses were carried out by considering different: LID systems, spatial scales, weather conditions, modeling investigation, as well as mathematical optimization approaches. Monitored data at the full scale implementation and laboratory measurements were used to support the numerical modeling. More in detail, first a global sensitivity analysis (GSA), based on the Elementary Effect Test (EET) was applied to a PCSWMM hydrodynamic model of the University Campus Innsbruck, which combines traditional drainage infrastructures and low impact development techniques, as Rain Gardens. In this regard, main findings have showed that soil hydraulic parameters considered in the model, (i.e., principally Soil Hydraulic Conductivity and Seepage Rate) were the most sensitive parameters. Therefore, the identification of these properties for LID systems is crucial in order to correctly evaluate their hydraulic performance. Starting from this finding the analysis of the hydrological efficiency of a full-scale extensive green roof, located at University of Calabria in Mediterranean Climate was assessed, by considering field monitored hydrological data, as well as soil hydraulic properties evaluated in lab, and a modeling analysis. Thus, first a field monitoring campaign for one year was carried out, and then hydrological performance indices on an event scale were evaluated. The findings have revealed the optimal behaviour of the specific green roof in Mediterranean climate, which presents an average value of Subsurface Runoff Coefficient of 50.4% for the rainfall events with a precipitation depth more than 8 mm. Later, to evaluate the influence of increasing values of substrate depths (6 cm, 9 cm, 12 cm, 15 cm) on green roof retention capacity, the hydraulic properties of the soil materials were first investigated in Laboratory, by the simplified evaporation method, and then considered for the implementation of the mechanistic model HYDRUS 1D. The results obtained in this phase have showed how the considered substrate depths were able to achieve a runoff volume reduction of 22% to 24%. Thus, as the outflow volume reduction achieved by increasing the soil depth was not significant, the ideal depth for specific soil substrate would be 6 centimetres. Following this study, and based on the findings obtained at building scale, next phase was focused on the analysis of hydrological effectiveness of Low Impact development solutions at largeurban scale in a south Italian case study. This investigation was carried out by considering different LID conversion scenarios by a predictive conceptual model (PCSWMM). In this regards, a specific permeable pavement and green roof, developed and installed at University of Calabria, were considered for the model implementation. Globally, modeling results have confirmed the suitability of these LID solutions to reduce surface runoff even if just a small percentage (30%) of the impervious surfaces is converted. By considering all of the findings, previous achieved by experimental and modelig investigation, it emerged that many aspects related to LIDs design and operation, as well as the choice of the facility and its location can affect the results in terms of hydraulic efficiency. In this regard, a mathematical optimization approach to consider several aspects together could be a suitable tool for designers of LID systems and experts in the field. Therefore, in the last part of the work, new Mathematical Optimization Approaches for LID techniques were evaluated. More in detail, the optimization of rainwater harvesting systems, by using TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) and Rough Set method as Multi-Objective Optimization approaches, was carried out. The results have demonstrated that these approaches could provide an additional tool to identify the ideal system. In conclusion, main findings of this thesis confirm the suitability of LID systems for urban stormwater management providing useful suggestions for their design and tools for assessing their hydrological effectiveness, analysing physical and hydrological parameters that affect their operation, introducing advanced concepts for the optimization of LID systems, therefore providing a significant and innovative contribution for the improvement of scientific research in the field and the spread of these sustainable techniques.
  • Thumbnail Image
    Item
    Post-failure analysis of landslides using the material point method
    (Università della Calabria, 2020-03-05) Pugliese, Luigi; Furgiuele, Franco; Troncone, Antonello
    Slope stability analysis is undoubtedly one of the most complex problems that civil engineers deal with. The evolution of deformation mechanisms of slopes is commonly schematized in four different stages: pre-failure, failure, post-failure and eventual reactivation. Traditional numerical methods, such as the finite element method and the finite difference method, are commonly employed to analyze the slope response in the pre-failure and failure stages under the hypothesis of small deformations. On the other hand, these methods are unsuitable for simulating the post-failure behavior due to the occurrence of large deformations. However, an adequate analysis of this latter stage and a reliable prediction of the landslide kinematics could be particularly useful for minimizing the associated risk or to establish the most suitable mitigation measures for land protection. Among the numerical techniques which have been recently developed to overcome the above-mentioned limitation, the material point method (MPM) is employed in this dissertation to analyze the post-failure stage of two real landslides: the Senise landslide (Basilicata) and the Maierato landslide (Calabria), both in Southern Italy, occurred in 1986 and 2010, respectively. The numerical analyses allow to faithfully simulate the real phenomena. In particular, with referring to the Senise landslide, the numerical analysis provides results that match satisfactorily well the field observations when both the slip surfaces detected by the installed inclinometers are accounted for. Besides, the lowest values of the shear strength parameters obtained from the laboratory tests have to be used. Moreover, an improvement of results is gained accounting for the presence of the existing structures as well. Concerning the Maierato landslide, symbol of the hydrogeological instability in Calabria (Southern Italy), the analysis performed using the material point method allows to successfully simulate the observed phenomenon, despite the complexity of this landslide regarding its size, catastrophic failure and long run-out distance. The obtained results demonstrate that an adequate analysis of the post-failure stage can lead to a better understanding of the complex mechanical mechanisms that characterize some landslides, and therefore help significantly to establish the most effective stabilization measures.
  • Thumbnail Image
    Item
    Resilienza e rischio nella rilettura urbanistica dell'emergenza. Il ruolo della viabilità strategica
    (Università della Calabria, 2020-02-18) Gaudio, Sara; Furgiuele, Franco; Francini, Mauro
    Urban systems are increasingly experiencing processes of evolution, change and transition. Therefore, there is an urgent need of identifying new planning approaches aimed at promptly responding to them. Over the years, the themes of risk and security have, more or less sponta-neously, contributed to direct the ways of governing the territories. However, the most recent crises have shown how many critical issues have remained unresolved. In this respect, new challenges have to be faced, especially in terms of emergency planning. Starting from a theoretical reflection on the current planning orientation and on the concept of urban resilience, this research tries to use a novel meth-odological approach with a view to provide a new characterisation to Emer-gency Plans, more spatial and not just operational. Following the need to identify some categories of relevant urban elements on the territory, the proposed performance-based framework offers a formal procedure for the detection of strategic road infrastructures. The obtained results allow to plan already in “peacetime” the best alternative routes to ar-rive safely in the areas established by Civil Protection in case of event and to facilitate rescue operations. Therefore, the analysis of the physical and functional relationships among different elements of the territory shifts the focus of emergency from a piece-meal approach to a more integrated one. This will be capable of addressing more consistently the future decisions concerning the urban structures, typi-cal of ordinary territorial planning.
  • Thumbnail Image
    Item
    New one-line model for shoreline evolution at beaches composed of not cohesive grains of any size
    (2020-02-18) Francone, Antonio; Furgiuele, Franco; Tomasicchio, Giuseppe Roberto; Frega, Ferdinando;
    Over recent decades, efforts have been made to find robust methods for predicting shoreline evolution near to the coastal structures. This requires a rigorous understanding of the key coastal processes that drive sediment transport, and how they are impacted by the presence of structures. Once this understanding is reached, a method for predicting morphological shoreline evolution is required. In this context, numerical modelling plays an important role. A new one-line model for shoreline evolution at beaches composed of not cohesive grains of any size is proposed: the General Shoreline beach (GSb). GSb model is based on the one-line theory, for which it is assumed that the equilibrium beach profile remains unchanged (Dean, 1990), thereby allowing beach change to be described uniquely in terms of the shoreline position. The longshore sediment transport rate is estimated by means of a general formula/procedure (Tomasicchio et al., 1994; Lamberti and Tomasicchio, 1997; Tomasicchio et al., 2013; Tomasicchio et al., 2015) combining an energy flux approach with an empirical/statistical relationship between the waveinduced forcing and the number of moving units. The uniqueness of the proposed new one-line model consists in the possibility to simulate beach change, including the effects of coastal structures (i.e. groynes, detached breakwaters), at a mound composed of not cohesive grains of any size, from sand to rock units. Despite other existing models, the GSb model presents a calibration factor, KGSb solely and it has been calibrated and verified against field and laboratory data on sandy and mixed beach (sand and gravel) referring to simple groyne and detached breakwater (Ming and Chiew, 2000; Hamilton et al., 2001; Martin-Grandes et al., 2009; Medellin et al., 2018;). Optimal values of KGSb, valid for different types of not cohesive grains and coastal structures, have been reported. It is showed that the GSb model can be considered a reliable engineering tool to conduct morphodynamics studies. A demo version of the GSb model, for Mac and Windows systems, has been released for the scientific community and is available at www.scacr.eu.
  • Thumbnail Image
    Item
    Lo sviluppo dei sistemi di trasporto collettivo: studio di un indice per la determinazione del comfort a bordo.
    (2017-06-16) Tassitani, Antonio; Furgiuele, Franco; Astarita, Vittorio
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Soluzioni innovative per lo sviluppo della mobilità sostenibile: aspetti metodologici e sperimentali
    (2017-06-16) Rogano, Daniele; Furgiuele, Franco; Guido, Giuseppe
  • Thumbnail Image
    Item
    Turbulence characteristics in open-­‐channel flows with highly rough beds.
    (2017-10-27) Ferraro, Domenico; Furgiuele, Franco; Gaudio, Roberto
    River motion is one of the most attractive and fascinating phenomena in nature. Since ancient times many scientists have been drawn into a vortex of confusion observing river motion. Flow observation is often simplified, running tests in a laboratory under controlled conditions, in order to test a specific phenomenon of a much more complex issue. A great number of these phenomena has been collected by researchers throughout the history of science, and other researchers have tried to merge the available knowledge to clarify the tangled phenomena. This work is focused on the turbulent characteristics of Open-Channel Flows (OCFs) over a highly rough bed. The use of coarse sediments is an attractive technique to solve many problems in rivers as well as to safeguard aquatic life. Issues like sediment transport phenomena or erosion and local scour, e.g. at bridge piers and abutments, can be counteracted by introducing coarse sediments. In this work the bed roughness effect on the turbulence characteristics of the flow is investigated through the relative submergence parameter Δ, which is the ratio between the roughness characteristic dimension and the water depth. Most of the theories and literature works has been developed for smooth-wall flows and rough-bed flows at very high relative submergence, whereas its applicability in OCFs with low relative submergence remains questionable; the simplest example is the velocity distribution (i.e., the universal logarithmic law). This thesis aims at improving the knowledge of turbulence structure developed over a highly rough bed in OCFs by varying the relative submergence. According to the relative submergence definition given before, it can be changed by modifying the water depth for a fixed roughness or varying the roughness keeping the water depth constant. The choice settled on the second strategy, because of the measurement instrument configuration. It will be described in detail in the chapter “Experimental equipment and procedures”. The relative submergence varied in the range from 3.13 to 10.07. Three long-duration experiments (each one with a given coarse sediment size) were performed in uniform flow conditions by using a 100 Hz ADV down-looking probe, in order to record the 3D velocity vector in each point of a given grid of measurements. The contribution of the Reynolds stress, the viscous and the form-induced shear stress was analysed, as well as the averaged velocity profiles, second- and third-order moments . A statistical tool will be proposed to verify the frozen-in Taylor hypothesis by comparing two typical time-scales, namely the large scale advection time and the characteristic nonlinear time. The proposed method based on the characteristic eddies timescales is more restrictive with respect to the classic frozen-in Taylor hypothesis, in which a simple comparison of the flow velocity and the fluctuation magnitude is made. Furthermore, one-point temporal correlations analysis will be performed in order to give a first indication of the integral scales lengths along the channel varying the relative submergence. Spectral analysis is introduced both in the frequency and in wavenumber domain. In experimental practice it is quite hard to obtain direct measures, which can allow computing directly a wavenumber spectrum. Temporal velocity signals are commonly recorded in a single point, and they are used to compute the frequency spectrum and then converted to wavenumber spectrum through the Taylor frozen-in hypothesis. Hence, the k−5/3 slope is investigated in the longitudinal velocity spectra. k is the wavenumber. Spectral analysis will be introduced in order to test the observed k−5/3 slope, in order to confirm that the inertial subrange is well visible at the investigated Re numbers. Furthermore, the validity of the −5/3 scaling region will be also tested by using the third-order longitudinal velocity structure function, which is expressed as a function of the turbulent kinetic energy (TKE) dissipation rate. The third-order longitudinal velocity structure function will be also used to provide an estimate of the magnitude of the TKE dissipation rate. In addition, in order to quantify the energy contribution of different eddyscales, premultiplied spectra will be employed. Thanks to this analysis, the Large Scales (LSs) and the Very Large Scale (VLSs) will be investigated. These scales will be associated with a characteristic wavenumber and intensity. ADV velocity measurement also allows exploring the longitudinal-vertical velocity co-spectra. In order to locate the normalized wavenumber associated with the peak in the premultiplied spectra, a systematic procedure to find the correct position of the peaks based on the center of mass concept will be proposed. Moreover, the peak distribution over the water depth will be plotted in inner and outer coordinates.
  • Thumbnail Image
    Item
    <> modello di gestione delle reti idriche in condizioni di emergenza
    (2017-06-16) Caruso, Olga; Furgiuele, Franco; Fiorini Morosini, Attilio