Papers
|
Papers
Info
Experiences with SWASH on modelling wave propagation over vegetation: comparisons with lab and field data
The vegetation capacity to protect the coasts from wave action is becoming more important and attractive due to ongoing sea level rise and increasing storminess. In addition, it is a quite environmentally friendly way. Quantifying the vegetation effect in wave propagation will be relevant for coastal management. A non-hydrostatic wave model based on the nonlinear shallow water equations, SWASH, offers opportunities to quantify the wave dissipation effect in vegetation fields. However, limited applications of SWASH addressing this subject can be found in the literature and therefore it is important to enhance the existing knowledge on the model behaviour. In this research, in order to understand the characteristics of the SWASH model further, the model is applied to reproduce the significant wave height (Hs ) evolution over vegetation fields measured in flume experiments and in field campaign. Overall, SWASH performed very well in reproducing the Hs evolution measured both in the laboratory and in the field. In the case of flume data, the statistical scores MBE, RMSE and MRE, showed that the SWASH performance clearly improved when increasing the number of vertical layers assumed in the simulations. In the case of field data, considering a vegetation factor (Vf ) between 0.1 and 0.5, that represents the overall effect of scarcely known numerical vegetation parameters, led to a fairly good SWASH performance in modelling the Hs evolution over vegetation.
Year: 2020
Number Pages:
145-150pp.
Author(s): Reis, R.; Pires Silva, A.; Fortes, C. J. E. M.; Suzuki , T.
: Revista de Gestão Costeira Integrada
Editor: APRH
Volume:
20(2).
Keywords: Model-data comparisons; Wave dissipation; SWASH model; Vegetation; Wave propagation
Info
Exploring teenagers' spatial practices and needs in light of new communication technologies
There is an increasing awareness and advocacy claim for engaging the society in the production of public openspaces. This contribution seeks to increase knowledge on the relationship between spaces and the social practicesof teenagers, towards a more inclusive and interactive process of public space co-creation. It is based on twoEuropean Projects: CyberParks and C3Places, and explores teenagers' spatial practice and needs, and how toengage them in the process of co-creating more sensitive public spaces, while exploring the challenges andopportunities ICT open. It this paper, the results of a case study taking place in Lisbon and the analysis ofquestionnaires and interviews are discussed.
Year: 2020
Number Pages:
7p.
Author(s): Costa, C.; Batista, J.; Almeida, I.; Menezes, M.
: Cities
Editor: Elsevier
Volume:
98.
Keywords: Lisbon; Living labs; Spatial needs; Neighbourhood; Teenagers; Public open spaces
Info
Flooding occurrences in the portuguese continental coastal zone: a database for the period 1980-2018
The Portuguese continental coastal zone is characterized by its lithological, morphological, biological and landscape diversity. With a coastline extension of approximately 987 km, this zone has great importance in the national context. The increasing anthropic occupation of the coastal zone in the last seven decades led to a conflict with the natural dynamics of these areas. The project MOSAIC.pt emerges from the need of a comprehensive flood risk management framework for the Portuguese coastal zones, including estuaries. One of the innovative challenges of this project is to identify the coastal critical typologies affected by flooding, based in historical data. Hence, a historical database of coastal flood occurrences was created for the period 1980-2018. Historical data was collected in national and regional newspapers. The database includes relevant information such as flood triggering factors and impacts. For the period 1980-2018, a total of 398 occurrences of coastal overtopping and flooding were identified. The analysis shows that the vast majority of occurrences are located on the Portuguese western coast. In terms of impacts, the typologies associated with material, natural, environmental and lastly human impacts stand out. Results provide relevant temporal and spatial information about coastal historical flood occurrences and contribute for the design of a risk framework.
Year: 2020
Number Pages:
7p.
Author(s): Barros, J.; Freire, P.; Perdiz, L.; Tavares, A.
: e-proceedings of the 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL2020 PSAM15), 01 06 November 2020 Venice, Italy. Edited
Editor: Research Publishing Services
Keywords: Occurrences; Impacts; Database; Flood; Coastal zone
Info
Hybrid monitoring-modelling analysis on the storm induced sediment dynamics of a structure-controlled beach
The main objective of this study is to investigate the effect of sediment flushing on the morphology of artificially embayed beaches using field data and numerical modelling. The sandy stretch of Cova-Gala in the West Coast of Portugal, characterized by a high-energy wave climate, is critical regarding erosion-flooding risks. The site was monitored from August 2018 to February 2019, including the wave climate, the sea level and the beach topo-bathymetric elevation via sonar-single beam, GNSS-RTK and drone surveys. During this period several erosive events caused the retreat and lowering of the upper beach profile. The XBeach model was applied to simulate the morphological evolution during the monitored period using synoptic wave and sea level data as the hydrodynamic forcing. The results of the data-model analysis reveal that i) the alongshore extension of the sedimentological cells and the cross-shore structures length have a relevant influence on the lee-side erosion patterns, which affect the overall surrounding morphology, ii) the model overestimates the scouring of the seawall toe, particularly with the 1D mode; and iii) the beach backshore typology, dune and seawall, has a great influence on beach dynamic processes.
Year: 2020
Number Pages:
605-609pp.
Author(s): Oliveira, J. N.; Oliveira , F.; Freire, P.; Teixeira, A.
: Journal of Coastal Research
Editor: Coastal Education and Research Foundation (CERF)
Volume:
SI 95.
Keywords: coastal monitoring, XBeach, erosion.; numerical modelling; Beach morphodynamics
Info
Importance of infragravity waves in a wave-dominated inlet under storm conditions
The processes associated with infragravity waves (IGW) and their role on the hydro-sedimentary dynamics of a wave-dominated inlet are investigated using field observations collected at the Albufeira Lagoon (Portugal) during storm Leslie in October 2018. During the storm, significant IGW heights reached up to 1.0 m in the surf zone and 0.4 m inside the lagoon. IGW frequencies were blocked by ebb currents at the flood-delta and this effect was stronger for higher IGW frequencies. Therefore, low-frequency IGW were able to propagate further into the inner lagoon. The application of a 1D energy balance equation suggests that depth-induced breaking and bottom friction contributed equally to dissipate IGW energy at the flood-delta and that this dissipation was stronger during the flood than during the ebb. Large horizontal velocities under IGW crests increased the instantaneous suspended sediment transport rate by up to two orders of magnitude during flood at the flood-delta. The net suspended sediment transport rate and its variability, associated with the wave motion, was positive (landward) during flood and negligible during ebb. These positive values were associated with large wave-induced orbital velocities, suggesting that waves were more effective than tidal currents in inducing suspended sediment transport. The oscillatory suspended sediment transport rate was directed towards the lagoon and dominated by IGW frequencies. The observed sediment accretion of the northern channel occurred during the most energetic IGW. The measurements presented in this study and their analyses demonstrate how IGW play a major role in the sedimentary dynamics of wave-dominated inlets during storm conditions.
Year: 2020
Number Pages:
1-15pp.
Author(s): Mendes, D.; Fortunato, A. B.; Bertin, X.; Martins, K.; Lavaud, L.; Silva, A. N.; Pires Silva, A.; Coulombier, T.; Pinto, J.
: Continental Shelf Research
Editor: Elsevier
Volume:
192.
Keywords: Waves; Infragravity
Info
Influence of laboratory aggregate compaction method on the particle packing of stone mastic asphalt
The type of aggregates and their packing characteristics under compaction are key factors for the design of asphalt mixtures with improved performance, namely, with respect to resistance to permanent deformation. A good example is Stone Mastic Asphalt (SMA), known by its stoneonstone structure. In the U.S.A., the aggregate particles packing characteristics in a SMA, specially the stoneonstone effect, are normally assessed using the manually dryrodded method. However, this method may not be representative of field aggregate particle packing conditions, which may compromise the SMA performance. This article presents new findings regarding aggregate laboratory compaction methods to optimise the coarse aggregate structure in a SMA. Particle breakage, bulk density, air voids (compacted & uncompacted skeleton) in the aggregate / coarse aggregate were assessed for existing methods as well as for new methods using existing compactors, but with different procedures and/or specific devices, e.g. Proctor hammer. The assessed methods were: (1) noncompaction; (2) manually dryrodded method; (3) established Proctor compaction; (4) modified Proctor compaction (light and heavy compaction) and (5) steel roller compaction. The 2 latter new methods aimed at mechanically simulating the dry-rodded method and the effect of field compactors, respectively. The results highlight that the new laboratory compaction methods developed with Proctor and steel roller compactor, provide a particle packing that is more representative of the field conditions, comparatively to other aggregate compaction methods.
Year: 2020
Number Pages:
10.
Author(s): Miranda, H.; Batista, F. A.; Antunes, M. L.; Neves, J.
: Journal homepage: www.elsevier.com/locate/conbuildmat
Editor: Construction and Building Materials
Keywords: Stone mastic asphaltParticle packingStoneonstoneAggregate compaction methodsAir voids in coarse aggregate mixture
Info
Influence of the aggregate skeleton matrix and volumetric composition on the resistance of stone mastic asphalt to permanent deformation
The influence of different aggregate skeleton matrices, as well volumetric composition and mixture stiffness, on the resistance of SMA to permanent deformation was assessed. Nine SMA withdifferent optimised aggregate skeleton matrices, studied elsewhere, were now evaluated to permanent deformation with wheel tracking. The results were statistically analysed concerning relationship withspecimens volumetric characteristics, Marshall properties and mixture stiffness. Aggregate skeleton optimised with the dry rodded compaction tend to produce asphalt mixtures similar to SMA designedwith pre established grading envelopes. SMA with aggregate skeleton optimised with Proctor and steel roller compaction showed higher coarse aggregates and binder contents, and thus, it is expected abetter cracking resistance and durability for the same level of resistance to permanent deformation. Statistical analysis shows that the new proposed property (ratio between binder film thickness andporosity) and, ratio between Marshall stability and flow had the best correlations with permanent deformation properties.
Year: 2020
Number Pages:
14.
Author(s): Miranda, H.; Batista, F. A.; Neves, J.; Antunes, M. L.
: Journal Road Materials and Pavement
Editor: Journal Road Materials and Pavement - Taylor and Francis Online
Keywords: Stone mastic asphalt, stone-on-stone, mastic-within-stone, volumetric composition, permanent deformation
Info
Investigation of the Structural Dynamic Behavior of the Frontinus Gate
The Western Anatolia Region of Turkey is an important region of high seismic activity. The active dynamics of the region are shaped by a compression and expansion mechanism. This active mechanism is still ongoing and causes strong seismic activity in the region. The Frontinus Gate is a monument in the Roman city of Hierapolis of Phrygia located in southwestern Anatolia. The aim of this study is to investigate the seismic behavior of this stone masonry structure using discrete element modeling. For this purpose, nonlinear dynamic analyses were performed to simulate the structural response of the gate under seismic excitation. Deformation, damage, and failure patterns induced in the masonry gate for di erent levels of seismic action are evaluated and discussed. An earthquake with a return period of 475 years is expected to cause some damage, but no collapse, while for a return period of 2475 years, the models indicate collapse of the monument.
Year: 2020
Number Pages:
5821.
Author(s): Saygili, O.; Lemos, J. V.
: Applied Sciences
Editor: MDPI
Volume:
10.
Keywords: stone masonry; discrete element modeling; nonlinear dynamic analysis
Info
Large Scale Soil-Aquifer-Treatment (SAT-MAR) Physical Model Experiments to Improve Water Quality
The effluents from agriculture practices usually contain several contaminants creating an environmental concern to downgradient water bodies. The use of SAT systems to improve the effluents water quality, during the transport of infiltrated water through the unsaturated and saturated zones, can bring a solution for water reclamation, water reuse, and overall as a water resources management tool. The research was carried out under MARSOL project were SAT experiments were executed in a physical (sandbox) model. These experiments aimed to contribute solving the problem of removing rice field contaminants from water, using a soil-aquifer prototype basin to treat water prior to its discharge in Melides lagoon, Portugal. The sandbox model was divided into three sections to test the adsorption and biodegradation capacity of three soil profiles, two of them including soil mixtures of sand with vegetal compost with different layouts. In each section, two tracer experiments were performed with spiked fertilizer and hydrocar-bons. To analyse the tracers behaviour, monitoring devices were installed in three piezometers for continuous in situ readings of pH, T, EC, ORP and water level, besides water sampling hand-pump for chemical analysis. The results obtained in the experiments gave useful knowledge necessary to build an in situ facility.
Year: 2020
Number Pages:
8p.
Author(s): Leitão, T. E.; Martins, T.; Henriques, M. J. A.; Lobo Ferreira, J. P. C.
: VTGU journals
Editor: VGTU Press
Keywords: Agriculture water reclamation.; Physical model, water reuse; Soil-aquifer treatment (SAT)
Info
Long-term deformation of railway tracks considering train-track interaction and non-linear resilient behaviour of aggregates a 3D FEM implementation
Railway track designers and maintenance entities have long been pursuing for a robust and reliable method to predict the tracks long-term behaviour. The complexity of this railway system, in terms of its changing structural and material behaviour throughout its life cycle, have hindered that quest. This paper presents a novel computer implementation focused on the estimation of the ballast and sub-ballast long-term deformation that provides a realistic reproduction of the actual behaviour of the structures because (i) it considers the three-dimensional aspect of the problem, (ii) incorporates accurate non-linear resilient material laws for the granular layers, (iii) uses a robust constitutive high-cycle strain accumulation model specifically devised for railway tracks that accounts for the three-dimensional stress conditions to determine both the volumetric and deviatoric permanent deformations and (iv) explicitly considers the dynamic train-track interaction. After calibration and validation with the results from an experimental case study comprising a physical model, a simulation scenario, considering different train types, is presented to demonstrate the potential of this approach. This implementation allows the construction of sufficiently extensive and elaborate representations of the railway track, allowing the study of geometrically complex cases and of the influence of many other aspects on its long-term behaviour.
Year: 2020
Author(s): Varandas, J.; Paixão, A.; Fortunato, E.; Zuada Coelho, B.; Hölscher, P.
: Computers and Geotechnics
Editor: Elsevier
Volume:
126.
Keywords: Non-linear resilient behaviour; Three-dimensional numerical modelling; Railway tracks; Permanent deformation; Train-track interaction
|
