1,721,001 research outputs found
The effects of submerged berms on the stability of rubble mound breakwaters
No full textBerms deployed at the toe of conventional rubble mound breakwaters may be useful for various purposes, i.e. to reduce wave
loads acting on the breakwater armor elements, to reduce wave overtopping, to limit momentary liquefaction occurrences under
the structure and to protect from the scouring the breakwater toe.
In the first part, the Thesis is aimed to provide a new design criterion for the armor layer of conventional breakwaters with
submerged berms marked by small thickness compared to water depth. Indeed, past research studies focused on the influence
of relatively high berms on the stability of the armor layer. The design of the berm itself was not tackled herein. The effects of
submerged berms on the incident waves transformation have been evaluated by means of a numerical model, validated by
using experimental data. Then, a parametric correction factor of the incident significant wave height at the toe of the structure
is provided and included in well-established design criteria. The experimental comparison confirmed the reliability of the
proposed method by highlighting the importance to use design criteria within their validity ranges, in order to avoid an unsafe
dimensioning of the armor elements. In the second part, the Thesis is aimed to evaluate how
submerged berms configuration influence the seabed soil response and momentary liquefaction occurrences around and
beneath breakwaters foundation, under dynamic wave loading. The effects of submerged berms on the incident waves
transformation have been evaluated by means of the aformentioned phase resolving numerical model for simulating nonhydrostatic,
free-surface, rotational flows. The soil response to wave-induced seabed pressures has been evaluated by using an
ad-hoc anisotropic poro-elastic soil solver, developed within the OpenFOAM framework. Once the evaluation of the seabed consolidation
state, due to the presence of the breakwater, has been performed, the dynamic interaction among water waves, soil
and structure has been analyzed by using a one-way coupling boundary condition. A parametric study has been carried out
by varying the berm configuration (i.e. its height and its length), keeping constant the offshore regular wave conditions, the water depth and the elastic properties of the soil. Results indicate that the presence of submerged berms tends to mitigate the
liquefaction probability if compared to straight sloped conventional breakwater without a berm. In addition, it appears that
the momentary liquefaction phenomena are more influenced by changing the berm length rather than the berm height.
In the last part, the Thesis is focused on the role of submerged berms on the random wave-induced momentary liquefaction. A
numerical study has been carried out by selecting three ad-hoc domain, among those tested under regular wave condition. Indeed,
the influence of random wave loading on the momentary liquefaction occurrences is investigated through a comparison
with the corresponding representative regular wave results. Due to the wave randomness, the random wave-induced momentary
liquefaction depths are larger than the corresponding representative regular ones. This means that the evaluation of the
momentary liquefaction occurrences, under the action of representative regular waves, could underestimate the liquefaction
depth, determining an unsafe design in the practice
The influence of depth limited water conditions on the rock slope stability
Full text linkThe hydraulic stability of the armour layer of the rubble mound breakwaters have been widely discussed in the literature and
several empirical formulas have been proposed for design purposes. Nevertheless, few studies focused on the armour
stability in case of water depth limited water conditions.Then, the aim of the present research is to provide more
insights into the stability of the armour layer ranging from intermediate till extremely shallow water conditions. To this end, a 2D physical experiments have been carried out at the EUropean Maritime and Environmental Research (EUMER) laboratory of the University of Salento (Lecce), in presence of a 1V:30H foreshore. Tests aimed to investigate both the nearshore hydrodynamics and the hydraulic armour stability under different irregular waves attack. Experimental results are also compared with the damage evaluated from the empirical formulations available in literature, in order to investigate the predicted damage level in the shallowness
range analyzed
Nuovi esperimenti tridimensionali sulle onde di maremoto generate da frane su una costa rettilinea
No full textApproccio dinamico per la previsione degli eventi di Storm Surge in Adriatico
No full textIl presente lavoro descrive un nuovo approccio volto alla stima degli eventi di Storm Surge in Adriatico. L’idea di base è quella di applicare la teoria dei sistemi dinamici lineari al Mar Adriatico. In questo modo viene calcolata numericamente la funzione di risposta dell’intero bacino ad una tensione di vento unitaria diretta lungo l’asse principale dell’Adriatico applicata ad una serie di aree. La funzione di risposta ad un impulso unitario può essere utilizzata al fine di ottenere una serie di livello previsto non calibrata in un certo punto di interesse localizzato all’interno del bacino. La serie così ottenuta non ha la pretesa di predire esattamente il livello indotto da
un evento di storm surge, ma di offrire una serie temporale fisicamente basata da correggere mediante ottimizzazione statistica. L’articolo descrive la prima fase di lavoro volto alla costruzione della serie di livello non calibrata.This paper describes a new approach to estimate storm surge events in the Adriatic Sea. The main idea is to apply the theory of linear dynamical systems to the Adriatic basin. Indeed, the impulse response function of the whole basin to a unit wind stress directed along the main axis of the Adriatic Sea is numerically estimated.
Hence, the impulse response function can be used in order to get a raw level time series at a point of interest. The proposed method does not claim to forecast the water level due to a storm surge event exactly. Rather, it is a method that allows to get a raw level time series that may be correct with statistical approaches. The paper illustrates the first step to be carried out, i.e. the estimation of the uncorrected level time series
Tsunami waves generated by landslides on a plane beach: new three dimensional experiments
No full text
Nearshore sand mining for beach nourishment: the case study of the 2010 Abruzzo project (Italy)
No full textL'articolo descrive gli studi e le analisi eseguite a supporto del primo progetto italiano di ripascimento artificiale realizzato con sabbia di cava marina posta su bassi fondali. Gli interventi di ripascimento, conclusi nel 2010, hanno riguardato tratti della costa della regione Abruzzo.The paper describes the studies carried out in order to support the first Italian artificial beach nourishment made by nearshore sand mining. The beach nourishment works, completed in 2010, has been carried out along the coast of Abruzzo Region
Experimental optimization of the new Al Faw Port rubble mound breakwater
No full textL'articolo descrive le prove sperimentali eseguite per l'ottimizzazione della sezione corrente della diga a scogliera lunga più di 20 km posta a protezione del nuovo porto di Al Faw in Iraq. Le prove sperimentali sono state eseguite presso l'Università dell'Aquila nel Laboratorio di Idraulica Marittima e Ambientale LIAM.The paper describes the experimental tests carried out for the optimization of the current section of the rubble mound breakwater the new port of Al Faw in Iraq. Experimental tests were performed at the University of L'Aquila in the Laboratory of Environmental and Maritime Hydraulics LIAM
The Italian activities on tsunami risk mitigation: the operating landslide tsunami early warning system of Stromboli (Aeolian Islands, Italy)
No full textThe recent Italian research activities on tsunami risk mitigation are summarized in the paper.
The attention is focused on: field measurements, physical modelling of landslide generated tsunami, tsunami detection alghoritms, numerical and analytical models. Furthermore a synthetic description of the operating landslide tsunami Early Warning System of Stromboli
(Eolian Islands, Italy) is provided
Sistemi esperti per la previsione probabilistica del moto ondoso ai fini dell'operatività marittima
No full textL’esecuzione di particolari lavori marittimi, in mare aperto o in acque confinate, o la programmazione e/o la gestione di attività portuali possono richiedere la previsione del superamento da parte dell’altezza d’onda significativa di una prefissata soglia nell’ambito di una fissata finestra temporale con una probabilità di rischio nota. La presente memoria illustra una nuova metodologia per la previsione probabilistica dell’operatività di una finestra temporale, basata sulle previsioni deterministiche dello stato di mare fornite dai centri meteorologici
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