Papers
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Exploring the Applicability of Low-Cost Capacitive and Resistive Water Content Sensors on Compacted Soils
Soil water content measurement is crucial during compaction control of embankments. The current techniques used to measure the soil water content in the field are outlined, and their advantages and limitations are indicated. Most techniques require destructive sampling and yields late results, or involve expensive equipment and are hard to set up. Low-cost capacitive and resistive moisture sensors entered successfully in last decades in agronomy applications to automatize crops irrigation. The purpose of this study is to identify whether these sensors are reliable to be used in geotechnical engineering and, in particular, to what extent can they aid compaction control of embankments. Three resistive sensors and two capacitive sensors are tested on five types of soils prepared with a wide range of water contents. The experimental procedures are described, and the sensors output data are compared with water contents obtained from the oven-drying technique. A new device that allows calibration of the sensors on compacted soils is developed. Soils characteristics that can influence moisture measurement using capacitive and resistive sensors are also explored. Test results suggest that some of the sensors can estimate the soil water content on compacted fine grained soils, when proper calibration procedure is successfully achieved. Sensors accuracy tend to increase as the soil void ratio decreases. Such sensors may be useful for expedite measurements, especially, when later counter-prof is available, or when a wide interval for the water content is acceptable.
Year: 2021
Number Pages:
2929-2983pp.
Author(s): Teixeira, J.; Santos, R. N. C.
: Geotechnical and Geological Engineering
Editor: Springer
Volume:
39.
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Effect of the clump size for bonded particle model on the uniaxial and tensile strength ratio of rock
The Discrete Element Method (DEM) has been increasingly used to study the behaviour of rock. Despite theadvantage of classical DEM formulations in using simple interaction laws to model fracture initiation and propagation, they have limitations to properly simulate brittle rock behaviour. The code cannot predict the highvalues of unconfined compressive strength/tensile strength (UCS/TS) ratio associated with non-linear failureenvelopes, as observed for hard rock, such as granite, unless significant modifications are made. This paperproposes and implements a clumped-particle model into a two-dimensional DEM code. The increase in theinteraction between discrete elements, which locally increases the density of interparticle bonds, can improvethe results to obtain the desired values of UCS/TS ratio. This approach seems able to significantly increase both the potential and the predictive capabilities of DEM for rock modelling purposes. The novelties introduced in this work are the presentation of a numerical procedure to determine the equivalent micro-mechanical properties of intact rocks and, aware of a gap in our knowledge, the characterisation of uncertainties that a clumped-particle model introduces in the numerical results. A series of numerical simulations, including uniaxial compression and direct tension tests, were carried out, by varying the relation between the clump and the minimum particle radius, using the Monte Carlo simulation technique. The results were compared with experimental data on Lac du Bonnet granite, from the bibliography, which allowed to determine the equivalent micro-mechanical properties. Results, from a simulation using a core sample of Lac du Bonnet granite, show that the variance in the values of the mechanical properties calculated decreases with the decrease in the particle radius, but the influence of the clump size on the behaviour requires the execution of a considerable amount of simulations to achieve results with an acceptable relative error of 5%. Nevertheless, the mechanical behaviour obtained from DEM simulations was in good agreement with the experimental data and the model captured both the tensile and the unconfined compression strength values.
Year: 2019
Number Pages:
131-140pp.
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
Editor: Elsevier
Volume:
114.
Keywords: Clumped particles; UCS/TS ratio; Brittle behaviour; Discrete element method
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Suffusion evaluation of coarse-graded soils from Rhine dikes
An experimental study on internal erosion of coarse-grained soils collected from the Rhine River is presented. The tests performed on laboratory column aim to assess the potential of such soils to suffusion and to characterize their stability and the variation of the soil physical parameters during the suffusion process. An experimental device (large vertical column with 60 cm of height and 26 cm of diameter) has been developed, which allows the application of upward flow to noncohesivesoils under controlled hydraulic loading. The investigation of the parameters affecting the suitability of the soilsto suffusion leads to the identification of the hydraulic gradient that initiates the migration of particles to the outlet. The results show an increase in permeability, which is related to the migration and the washing out of fine particles in the upper layer. The particle size distribution of the downward soil layer after test is performed, and the analysis corroborates the localization of particles suffusion. The grain size analysis of the outlet shows that eroded particles are smaller than 500 lm and their size rather increases with increasing hydraulic load. Usual methods based on geometrical criteria proved to overestimate the susceptibility to suffusion of soils from the Rhine, and, therefore, one consider that, for such soils, it is preferable to carry out laboratory tests to evaluate the suffusion process.
Year: 2019
Number Pages:
815-823pp.
Author(s): Benamar, A.; Santos, R. N. C.; Bennabi, A.; Karoui, T.
: Acta Geotechnica
Editor: Springer
Volume:
14(3).
Keywords: Suffusion; Sandy gravel; Rhine river; Laboratory tests; Internal erosion; Dykes
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A constitutive model for soil-rockfill mixtures
Soil-rockfill mixtures (SRMs) are economical and environmentally friendly materials. Due to the absence in theliterature of constitutive models specifically developed and tested for SRMs, a new constitutive model, theSubloading Surface Rockfill Model, is presented. This model allows the occurrence of plastic strains inside the yield surface, inducing a smooth elastic/plastic transition. The results of experimental tests for different coarse fractions (CF) of several SRMs performed on samples from Odelouca Dam are compared with those obtained with this model. The model was able to reproduce reasonably well the response of SRMs considering the intrinsic variability of the tested specimens.
Year: 2018
Number Pages:
11p.
Author(s): Brito, A.; Maranha, J. R.; Caldeira, L.
: Computers and Geotechnics
Editor: Elsevier
Volume:
nº 95.
Keywords: genetic algorithms; constitutive modelling; subloading surface plasticity; soil rockfill mixture
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Crushing and oedometer compression of rockfill using DEM
A new methodology was developed to perform computer simulations of crushable rockfill particles using the dis-crete element method. Rockfill was modelled using a clump logic, responsible for providing a statistical and spatial variability in the strength and shape of the particles. Clumps have a major advantage of severely decreasing the number of contact equations to be solved in the model, resulting in less computer time. A series of single-particle crushing tests and an oedometer test were simulated using crushable particles and were in agreement with experimental data. A comprehensive study of the brittle failure of single-particle crushing tests is presented.
Year: 2018
Number Pages:
11-22pp.
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
: Computers and Geotechnics
Editor: Elsevier
Volume:
101.
Keywords: Clumps; Bonded particles; Crushing strength; Particle breakage; Discrete element method; Rockfill
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Hydromechanical characterization of soil-rockfill mixtures
In order to improve the rather insufficient knowledge about the hydromechanical behavior of soil
Year: 2018
Number Pages:
04018123p.
Author(s): Brito, A.; Caldeira, L.; Maranha, J. R.
: Journal of materials in civil engineering, ASCE, issue 7
Editor: Journal of materials in civil engineering, ASCE
Volume:
Vol. 30.
Keywords: permeability tests; hydromechanical behavior; mechanical tests; soil-rockfill mixtures
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Experimental study on limitation of internal erosion in dams by upstream zones of well-graded soils
The limitation of the progression of internal erosion in zoned dams, potentially caused by an upstream zone built of coarse, well-graded soils with non-plastic fines, is assessed using a new test cell. This device allows two types of tests to be conducted: the flow-limiting erosion test (FLET) and the crack-filling erosion test (CFET), which are designed to study the isolated influence of the flow-limiting action and the crack-filling action, respectively. The specimen is subjected to water flow along a hole drilled in the core and the upstream zone. In the CFET, the specimen additionally includes a downstream filter. Three upstream materials with non-plastic fines, a core and a filter are examined. The results of nine FLETs and nine CFETs are presented and analysed. The FLETs show the clear influence of the compaction water content, fines content and gravel content of the upstream soils in their capability to provide the flow-limiting action. The CFETs show that the specimen using the coarsest upstream soil (with 21% non-plastic fines) compacted on the dry side is capable of stopping the progression of erosion, enabling a partial crack-filling action. In all other test conditions, the filtering mechanism due to erosion of the upstream soil provides an important limitation of the erosion process. Based on the tests, practical recommendations to assess the influence of upstream zones on the limitation of internal erosion are proposed.
Year: 2017
Author(s): Santos, R. N. C.; Caldeira, L.; Maranha das Neves, E.
: Géotechnique
Editor: ACE
Volume:
67(6).
Keywords: laboratory tests; filters; erosion; dam
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Experimental study on crack filling by upstream fills in dams
The paper presents the main results of a research study into the crack-filling ability of granularmaterials located upstream of an erosion path in the core of a zoned dam. Upstream crack fillers areusually considered in dams located in zones of high seismic activity, as a redundant element, should acrack develop in the core and the downstream filter fail to retain the eroded particles. Uniform soilsof fine-sand size are highly effective at filling cracks and stopping the progression of erosion; however,they can be significantly expensive. In the interest of reducing the costs of their overuse, anexperimental investigation is conducted of the extent to which gap-graded sandy gravels that arenaturally present during the construction of dams can safely provide the crack-filling action. It wasconcluded that the sand content of the upstream material that is susceptible to suffusion, and itsrelation with D15F of the filter, is critical for rapid crack filling to occur. Other parameters influencingcrack-filling ability are the gravel content, the fines content and the type of the fines in the upstreamsoil. Practical rules to estimate the likelihood of crack filling by an upstream granular material beingeffective at stopping the progression of internal erosion along a concentrated leak in zoned dams arealso proposed.
Year: 2015
Number Pages:
218-230pp.
Author(s): Santos, R. N. C.; Caldeira, L.; Maranha das Neves, E.
: Géotechnique
Editor: ICE
Volume:
65(3).
Keywords: Laboratory tests; Filters; Erosion; Dams
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Laboratory test for evaluating crack filling during internal erosion in zoned dams
A new laboratory test, the crack-filling erosion test (CFET), was developed to study crackfilling during the progression of internal erosion in the embankment of zoned dams. Crackfilling involves the transport of eroded material from an upstream zone, through a flaw inthe core, which is then retained by a downstream granular layer. In the CFET, the specimencomprises a core, an upstream shell material, and a downstream filter layer. These arecompacted inside a test apparatus made up of several pieces. The specimen is subjected towater flow through a predrilled hole in the core to simulate a concentrated leak. Sevengranular upstream materials, two core soils, and two granular filters are examined. Followingan extensive testing program, experimental observations and physical descriptions arepresented. Three main types of pattern behaviors are identified: rapid crack filling withalmost
Year: 2015
Number Pages:
915-928pp.
Author(s): Santos, R. N. C.; Caldeira, L.; Maranha das Neves, E.
: Geotechnical Testing Journal
Editor: ASTM
Volume:
38(6).
DOI:
10.1520/GTJ20140074
Keywords: Upstream zone; Crack-filling; Cracking; Internal erosion; Zoned embankment dams; Test apparatus
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Laboratory test for evaluating limitation of flows during internal erosion in zoned dams
A new laboratory test, named the flow limitation erosion test (FLET), has been designed anddeveloped to study upstream flow limitation during the phase of progression of internalerosion in the embankment of zoned dams. Upstream flow limitation may occur because ofthe presence of the shell or a transition zone upstream of a cracked core. In the FLET, thesoil specimen is composed of core and upstream shell materials. These are compactedinside a test apparatus made up of several pieces assembled in steps. Then the soilspecimen is subjected to water flow through a predrilled hole in the core material tosimulate a concentrated leak, initiated, for example, by large differential settlement orhydraulic fracture. In most tests, the hole is also drilled in the upstream material to simulatethe scenario in which the mechanism causing the flaw in the core is also likely to affect theupstream zone. Combinations of the same core material and several types of coarse-grainedupstream materials (broadly graded and gap-graded soils) are tested for a range ofcompaction conditions and hydraulic loads. It is shown that FLET is capable of assessingwhether there is upstream flow limitation and whether the internal erosion process stops,shows a trend of slowing down, or progresses. Upstream flow limitation is shown to bedependent on the fines and gravel content, fines plasticity, and compaction water content ofthe upstream material. In the particular case of the tested gap-graded soils, it is shown to bealso dependent on the initial gradient along the upstream material.
Year: 2014
Number Pages:
463-476pp.
Author(s): Santos, R. N. C.; Caldeira, L.; Maranha das Neves, E.
: Geotechnical Testing Journal
Editor: ASTM
Volume:
37(3).
DOI:
10.1520/GTJ20130104
Keywords: Upstream zone; Flow limitation; Cracking; Internal erosion; Zoned dams; Test apparatus
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Comunicação
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Designing a pre-load embankment for the construction of a stage over a sanitary landfill founded in soft soils
For World Youth Day event in 2023 (JMJ), the organizing committee selected an area in Parque das Naçõesthat met the imposed requirements, notably in terms of area (for 1 million spectators) and proximity to the Lisbon center.This area, on the other hand, has the distinction of being a sanitary landfill, which was sealed in 1997 as part of the EXPO98 interventions, and which previously, in 1995, experienced a large-scale landslide in the direction of the river, with a front of 300 m of extension, enveloping the foundation up to significant depths. The fundamental cause of the landslide, according to studies undertaken at the time, was the low undrained strength of the foundation's soft soils that were still in the subconsolidation phase, particularly at the deepest levels. Considering this scenario, LNEC performed limit equilibrium stability analyses as well as three-dimensional stress and strain finite-element analyses to estimate the magnitude and evolution of the settlements of the JMJ stage to be built in the southern area. The analyses carried out, the results of which are presented in the article, revealed the need of a pre-load embankment and were used to define criteria for the constructive phasing of the work, which was inherently dynamic and based on the outcomes of the monitoring system installed on site. Finally, values obtained from the monitoring system installed during the construction phase are compared to the values estimated during the design phase.
Year: 2024
Number Pages:
6p..
Author(s): Brito, A.; Carreto, J.
: Geotechnical Engineering Challenges to Meet Current and Emerging Needs of Society
Editor: CRC Press
Keywords: consolidation; slope stability; soft soils; pre-load embankment; Sanitary landfill
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GCP FINDER
A utilização de novas tecnologias na monitorização de estruturas de engenharia civil, com ouso de veículos aéreos não tripulados (VANT) ou varrimento laser, permite o desenvolvimentode técnicas de inspeção e de medição de deslocamentos em barragens de aterro. A qualidadedo modelo geométrico depende, de entre outros, da existência de pontos de controlo nasuperfície do terreno (GCP). No caso dos VANTs, no pós-processamento das imagens, aoidentificar os GCP nas fotografias é então possível corrigir a posição dos objetos no modelotridimensional. Dado o elevado número de imagens adquiridas em cada voo, é essencialagilizar este processo. Na presente comunicação descreve-se um algoritmo desenvolvido emconjunto pelo LNEC e pela UNL, que permite a identificação automática dos GCP e apreparação dos dados para o seu processamento na plataforma WebODM.
Year: 2022
Number Pages:
1569-1578.
Author(s): Marcelino, J.; Freire, O.; Manso, J.; Leite, D.; Marques, N.
Editor: Carlos Pina, José Manuel Catarino, Ana Sofia Louro, Teresa O. Santos
Keywords: Open Source Software; WebODM; VANT; Inspeção visual; Barragem
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Discrete numerical modelling of single-particle crushing and oedometric tests for different values of suction
Particle breakage plays an important role in rockfill mechanical behaviour.Under compression or shear, the crushing of particles modifies the grain size distributionand indirectly, the material permeability, their frictional properties and the correspondingcritical state. In order to study the breakage of individual particles, several approacheswere adopted using discrete element method (DEM). Some considered sub-particles joinedby bonding or cohesive forces, other replaced particles, which verified a predefined failurecriterion, by an equivalent group of smaller particles. In this paper, using the discreteelement method, a new methodology was developed. It consisted of modelling crushablerockfill particles using the clump logic, which was responsible for providing a statisticaland spatial variability in the strength and shape of the particles. Particle movementsand interactions were determined using DEM, allowing to determined the deformation ofthe rockfill material. Clumps have a major advantage of severely decreasing the num-ber of contact equations to be solved in the model, resulting in less computer time. Acomprehensive study of the brittle failure of single-particle crushing tests is presented.Preliminary tests on particle size evolution were also performed, assuming some simplifi-cations. No attempt was made to simulate the real particle size distribution (PSD), dueto the cost of simulating smaller particles. Single-particle crushing tests and oedome-ter tests were simulated using crushable particles, whose results were in agreement withexperimental data.
Year: 2021
Number Pages:
19p.
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
Editor: E. Oñate, M. Papadrakakis and B. Schrefler
Keywords: Suction stresses; Rockfill; Oedometer tests; Crushing tests; Discrete Element Method
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Estudo da fluência e da relaxação de enrocamentos em ensaios edométricos
Neste trabalho estuda-se experimentalmente a fluência e a relaxação de enrocamentosubmetido a diversos níveis de carga. Uma série de ensaios de relaxação foramrealizados num enrocamento para incrementos de 100 kPa até 1MPa, com patamaresde 24 horas. Um dos objetivos deste trabalho foi estudar a evolução granulométrica,durante os ensaios, e observar as diferenças entre os coeficientes de uniformidade(C u ) e de curvatura (C c ). Numa segunda fase do trabalho o objetivo foi estudar o efeitodo tamanho das partículas no comportamento do material, utilizando umagranulometria uniforme. Em cada ensaio foram observados dois tipos de deformações,sugerindo que a deformação pode ser dividida em componente instantânea e umacomportamento dependente do tempo.
Year: 2021
Number Pages:
8p.
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
Editor: Sociedade Portuguesa de Geotecnia
Keywords: Ensaios Edométricos; Enrocamento; Relaxação; Fluência
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Yielding of rockfill in triaxial experiments
In recent years, interest in rockfill mechanics has considerable increased, since it has been applied in many geotechnical structures throughout the world. Rockfill is commonly used in road and railway embankments, railway ballast and earth and rockfill dams. Whether its applied in concrete face rockfill dams or embankments for roadways or high-speed train lines, a precise prediction of expected deformations is needed. Since rockfill behaviour started being investigated that significant differences between rockfill and soils behaviour and characteristics were pointed out. A main difference is related to particle breakage, which depends on the strength of particles, particle size distribution, particle geometry and degree of weathering, stress level and relative humidity. Nonetheless, the effect of RH on rockfill behaviour has been neglected both in experiments and in constitutive modelling despite its fundamental effect. The importance of water action, for a wide class of rockfill materials, can be assessed analysing the behaviour of rockfill dams under reservoir impoundment or climatic conditions. This paper presents the results of triaxial tests performed on compacted specimens of a granite rockfill. Different aspects of the rockfill behaviour, important for constitutive modelling, were studied, namely the shape of yielding loci and the dilatancy rules. Dilatancy was described in terms of plastic work input and the shape of the yield locus, in a triaxial plane, was established by different experimental techniques.Yielding loci can be well represented by approximate elliptic shapes, whose major axis follows approximately the K0 line.
Year: 2020
Number Pages:
16p.
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
Editor: Fourth International Dam World Conference
Keywords: dilatancy; yielding loci; triaxial tests; Rockfill
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Settlement analysis of the Montesinho concrete-face rockfill dam
This paper studies the effect of suction in the rockfill materials and its influence in the behaviour of Montesinho CFRD. A three-dimensional FEM model has been developed incorporating the model of Oldecop and Alonso (2001) using the MFront software together with code-aster. The three major phases of the dam were simulated: construction, reservoir impounding and operation. In order to verify the adequacy of the model in describing the behaviour of the Montesinho CFRD, the results of the developed model were compared to the monitoring results. The model parameters used in this study were calibrated based in the experimental data collected from a set of experimental tests.Comparative studies of monitoring data and simulations showed good agreement between measured settlements and computed settlements, allowing to predict the deformation of the structure in the next 10 years. Overall, the deformation of the Montesinho CFRD is stable and the monitoring system used to control the dam deformation is successful.
Year: 2019
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
Editor: Proceedings of the XVII ECSMGE-2019
Keywords: Code-aster; MFront; FEM; Rockfill
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Assessment of water flow measurements in a zoned dam using artificial neural network models
This paper concerns about the assessment of the hydraulic behavior of a 50 m height zoned dam used for industry water supply, located in Alentejo region, in Portugal. The original draining system of the embankment is composed of a sub-vertical filter, located downstream of the central core, and by a drainage blanket placed over the foundation, in the deeper area of the valley, which, in turn, discharges to a downstream drainage toe.In this study, the achieved performance of neural network models to predict the flow rate in a drain was very good when compared with traditional multiple linear regression models. Despite the good results presented, it is necessary to carry out further studies including the results obtained from other individual drains, and it is not dispensable a global evaluation of the dam safety on the basis of a comprehensive analysis of the various observed parameters. Finally, it is always wise to carry out the safety evaluation simultaneously with various models rather than with just one model.
Year: 2018
Author(s): Santos, R. N. C.; Mata, J.
Editor: ICOLD
Keywords: Zoned dam; Flow measurement; Artificial neural networks; Earthfill dam
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Discrete numerical modelling of the mechanical behaviour of rockfill in a oedometer test with suction control
The effect of suction in the compressibility of rockfill along different stress paths is studiedusing the discrete element method. Rockfill particles are modeled as breakable clumpedparticles and reasonable consistency is found between the predicted and experimental results.The simulation highlights the influence of suction and the particle breakage on the mechanicalbehaviour of the assembly. The capabilities of the discrete element method are also explored tostudy the microscopic interactions that occur during the oedometer tests.
Year: 2018
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
Editor: Sociedade Portuguesa de Geotecnia
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Estudo da evolução granulométrica em ensaios edométricos de enrocamento, com controlo de sucção.
O comportamento dos materiais de enrocamento é fortemente condicionado pela resistência aoesmagamento das suas partículas. A resposta deformacional de um provete de ensaio resulta na roturados elementos de rocha, quando as tensões de contacto ultrapassam a resistência ao esmagamento, oude um rearranjo das suas partículas, até se atingir um estado de equilíbrio. É sabido que certos aspetosdo comportamento de enrocamento, como a compressibilidade e resistência ao corte, dependem datensão de confinamento e que essa dependência é afetada pela quebra das partículas. Recentemente,tendo surgido um crescente interesse no estudo da influência da sucção no comportamento do materialenrocamento, devido à sua importância na quebra das partículas, julga-se importante caracterizar estainfluência. Para melhor quantificar a quebra de partículas, vários investigadores propuseram diferentesíndices de quebra. Estes baseiam-se essencialmente nas curvas granulométricas antes e depois de cadaensaio. Para estudar o comportamento mecânico do enrocamento foram realizados ensaios no edómetrode grandes dimensões do LNEC, para diferentes trajetórias de tensões e sucções. Neste artigodescreve-se a evolução dos vários índices de quebra, propostos na literatura, e adotam-se três dosprincipais para estudar a evolução granulométrica. No final caracteriza-se o comportamento mecânico doenrocamento e avalia-se o desempenho de cada um dos índices de quebra, sugerindo-se o mais indicadopara aplicar em estudos futuros.
Year: 2018
Number Pages:
11p.
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
Editor: Sociedade Portuguesa de Geotecnia
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Settlement analysis of the Montesinho CFRD
Concrete face rockfill dams (CFRDs) are becoming a widely used type of rockfill dam all over the world. Until recently, the design and construction of CFRDs were empirically based primarily on precedent and engineering judgments. Few numerical or analytical methods have been developed to properly evaluate the deformation of CFRDs, which is important for dam safety and for subsequent evaluation of seismic performance. This paper describes the setup of a finite element method (FEM) model for the three dimensional simulation of the construction of Montesinho CFRD and filling of the its reservoir using the Code-Aster code. The prototype of the study is the 36.5 m high Montesinho CFRD, located in the north of Portugal near the Spain border, in the Sabor river in the Montesinho Natural Reserve, witch has been completed in 2016. Settlements are regarded as a key indicator of dam safety. Therefore, the time-dependent settlement behaviour of Montesinho CFRD is studied on the basis of in situ settlement-monitoring records. The monitoring results covered the construction period, the initial filling of the reservoir and 2 years of operation. Two different elastoplastic models (Druker Prager, Cam Clay) were implemented to better model the rockfill materials. The model parameters were calibrated by large-scale triaxial tests, performed on materials used in the dam. The numerical results agree well with in situ monitoring records of dam settlements, allowing to predict the deformation of the dam in the future.
Year: 2018
Number Pages:
16p.
Author(s): Manso, J.; Marcelino, J.; Caldeira, L.
Editor: Third International Dam World Conference
Keywords: settlements; FEM; rockfill; CFRD
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Books
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Projeto, construção e observação de pequenas barragens de aterro
Como é bem sabido, a realização de barragens, a par dos reconhecidos benefícios de váriaordem resultantes da sua exploração, pode envolver danos potenciais para as populações ebens materiais e ambientais na sua vizinhança, pelo que se torna indispensável assegurarum controlo da segurança dessas obras. Esses danos estão sobretudo associados aos efeitosda onda de cheia gerada pela rotura da estrutura. A que há que adicionar naturalmenteos custos associados à destruição da própria estrutura.
Year: 2015
Number Pages:
333-366pp.
Author(s): Portugal, J. C.
: Projeto, construção e observação de pequenas barragens de aterro
Editor: IST Press
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Capítulo de Livro
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Fundações
N/A
Year: 2005
Number Pages:
92p.
Author(s): Lopes, M. G.; Portugal, J. C.
: Construção de empreendimentos na práctica. Manual dirigido à aplicação e desenvolvimento de processos e métodos de uma construção
Editor: Verlag Dashôfer
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Tese de Doutoramento
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Experimental investigation on limitation of the progression of internal erosion in zoned dams
Two mechanisms limiting the progression of internal erosion in zoned dams, potentiated by the presence of materials located upstream of a damaged core are investigated. These are the flow restriction and crack filling actions. The former is related with the ability of the upstream soil restricting the flows passing through a flaw in the core. The latter involves transport of particles from the upstream zone into a flaw in the core, up to a downstream granular zone. A new apparatus is developed from scratch. It allows carrying out two innovative laboratory tests: the Flow Limitation Erosion Test (FLET) and the Crack Filling Erosion Test (CFET). Following an extensive testing programme on thirteen upstream materials, two cores, and two downstream filters, experimental observations and physical descriptions are presented. The potential soil behaviour patterns are described. The apparatus can assess whether erosion in the core stops, slows down, or progresses. The flow restriction action is governed by grading, plasticity and compaction characteristics of the upstream soil. In gap-graded with 5% of fines, the hydraulic loading and type of fines are critical. Crack filling by granular soils occurs rapidly, being governed by the sand and fines content of the upstream soil, and an effective grain diameter (D15F) of the filter. Rules for preliminary estimation of the likelihood of occurrence of the studied actions are also proposed.
Year: 2014
Author(s): Santos, R. N. C.
Keywords: Crack filling; Flow restriction; Upstream zone; Test apparatus; Concentrated leak; Internal erosion; Zoned dams
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Propagação e mitigação de vibrações de baixa frequência geradas por comboios de alta velocidade
Em Portugal serão construídas, nos próximos anos, algumas centenas de quilómetros de vias férreas de alta velocidade. As exigências associadas a estas linhas, em particular no que concerne a tolerâncias de fabrico, são, naturalmente, mais restritivas que as das linhas férreas tradicionais, onde circulam comboios de carga e de passageiros a velocidades mais reduzidas.Em diversos países tem-se verificado que a conjugação de velocidades elevadas de circulação com determinadas características dos solos de fundação conduz a fenómenos de amplificação dinâmica das deformações resultantes da circulação dos comboios.As linhas de alta velocidade, em Portugal, terão inevitavelmente de atravessar zonas onde a velocidade de circulação se pode associar com as condições desfavoráveis das fundações criando os fenómenos dinâmicos referidos.O presente Programa de Investigação situa o problema da circulação dos comboios de alta velocidade sobre solos moles, faz uma revisão dos métodos existentes para a previsão e análise do fenómeno, e analisa as medidas de mitigação existentes.Em resultado da análise do problema são perspectivadas diversas linhas de investigação que têm como objectivo: a identificação dos factores que contribuem e condicionam a geração e propagação das vibrações; o desenvolvimento de ferramentas de análise e previsão; a identificação e estudo das zonas que, estando no traçado das linhas de alta velocidade em Portugal, possuem as características que potenciam o desenvolvimento do fenómeno e, finalmente, conjugando o conhecimento resultante dos tópicos anteriores, a análise das medidas de mitigação mais adequadas para os casos identificados. Por último, é apresentado um Programa de Pós-Graduação, onde são concretizadas as linhas de investigação propostas, sob a forma de planos de enquadramento de recém licenciados, de teses de mestrado e de doutoramento.
Year: 2005
Author(s): Marcelino, J.
Keywords: Mitigação; Vibrações; Alta velocidade ferroviária
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Modelação física com centrifugadora
A primeira centrifugadora geotécnica portuguesa foi recentemente instalada (1994) noLaboratório Nacional de Engenharia Civil. Para tanto estabeleceu-se um plano de acçãovisando três objectivos principais. Por um lado, e dada a natureza pioneira à escala nacional daaplicação em causa fundamentar a técnica de modelação física proposta. Por outro,materializar os meios necessários à exploração do novo recurso. Finalmente, aplicar a técnicade modelação física, no âmbito de um plano de investigação que permitisse ilustrar as suaspotencialidades. Esta dissertação constitui o corolário desse programa de acção, reflectindo ostrês objectivos programáticos estabelecidos.
Year: 1999
Author(s): Portugal, J. C.
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Modelação do colapso e da fluência em aterros
RESUMOO presente trabalho visa fundamentalmente apresentar novas propostas na modelação dedeterminados efeitos característicos de aterros, especialmente quando se trata de aterros deenrocamento. Os efeitos visados, o colapso e a fluência manifestam-se pelo aumento dasdeformações dos aterros nomeadamente de barragens. No primeiro caso, as deformações sãoprovocadas pela molhagem do material e ocorrem de forma súbita, podendo implicarimportantes perdas de folga das barragens. No segundo, as deformações ocorrem de formadiferida no tempo e, por vezes, representam uma parcela significativa da deformação total.Passa-se em revisão os modelos de comportamento mecânico habitualmente utilizados nadescrição do comportamento dos materiais geotécnicos em modelos matemáticos, bem comoas técnicas e métodos numéricos, indispensáveis para a abordagem dos problemas específicosdas barragens.Propõe-se uma nova abordagem para modelar o colapso baseada na variação progressiva dosparâmetros das leis constitutivas. Apresenta-se ensaios de determinação das características decomportamento de materiais de enrocamento permitindo simultaneamente o estudo dadeformação de colapso. Desenvolvem-se técnicas ensaio que possibilitam nomeadamente, oestudo do comportamento do material à repetição de ciclos de molhagem-secagem e asimplicações que estes ciclos podem ter na deformação de colapso.Considera-se que a fluência pode ser tratada de forma análoga ao colapso excluindo a escalade tempo do fenómeno. Realizam-se ensaios que, à luz do modelo adoptado, permitem aferiros parâmetros que controlam a deformação de fluência no tempo.Os modelos desenvolvidos são aplicados ao estudo de dois casos reais de grandes aterros deenrocamento. No primeiro caso, apresenta-se uma retroanálise do comportamento dabarragem de Beliche, concluindo-se haver uma boa concordância entre os valores resultantesda observação da barragem e os resultados dos modelos propostos. O segundo caso, refere-sea um aterro de estrada com altura máxima de 40 m que está compreendido na empreitada deconstrução da barragem de Odeleite. Neste caso não se dispõe ainda dos resultados daobservação dos deslocamentos e, por esse motivo, os valores apresentados constituem umaprevisão de comportamento.
Year: 1996
Author(s): Marcelino, J.
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Relatório Científico
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Relatório de atividades: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP e Administração Pública de Timor-Leste 2011-2012
Neste relatório apresentam-se as atividades realizadas no período de 2011-2012 no âmbito do Programa deCapacitação dos Laboratórios de Engenharia dos PALOP e administração Pública de Timor-Leste,implementadas com recursos do Fundo Especial da CPLP, com a coordenação do Laboratório Nacional deEngenharia Civil (LNEC), na qualidade de instituição Proponente. Tem-se assim em vista fornecer aoSecretariado Executivo da CPLP elementos que permitam a realização do acompanhamento e monitorizaçãodas Atividades e a avaliação do cumprimento da metodologia e procedimentos propostos bem como o alcance dos resultados e objetivos previstos
Year: 2013
Author(s): Portugal, J. C.; França Martins, M.
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Relatório de atividades: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP 2010-2011
Neste relatório apresentam-se as atividades realizadas no período de 2010-2011 no âmbito do Programa deCapacitação dos Laboratórios de Engenharia dos PALOP, implementadas com recursos do Fundo Especial da CPLP, com a coordenação do Laboratório Nacional de Engenharia Civil (LNEC), na qualidade de instituição Proponente. Tem-se assim em vista fornecer ao Secretariado Executivo da CPLP elementos que permitam a realização do acompanhamento e monitorização das Atividades e a avaliação do cumprimento da metodologia e procedimentos propostos bem como o alcance dos resultados e objetivos previstos.A Proponente submeteu à CPLP um Relatório Técnico e Financeiro de Progresso da Atividade (RelatórioIntercalar) a meio do período de execução a que se refere este projeto.
Year: 2012
Author(s): Portugal, J. C.; França Martins, M.
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Projecto POCI/ECM 61114/2004
N/A
Year: 2009
Number Pages:
95pp.
Author(s): SILVA, J.; Caldeira, L.
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Modelo bi-dimensional para o estudo das vibrações devidas a comboios de alta velocidade
N/A
Year: 2007
Author(s): Marcelino, J.
Keywords: Vibrações; Mef; Alta velocidade ferroviária
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Modelo Bi-Dimensional para o estudo das vibrações devidas a comboios de alta velocidade
N/A
Year: 2007
Number Pages:
48pp.
Author(s): Marcelino, J.
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Avaliação preliminar das condições de segurança da barragem do Lapão
N/A
Year: 2002
Number Pages:
22pp.
Author(s): Marcelino, J.
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Programa MBE
O presente relatório apresenta sumariamente a motivação para a realização dos programas MBE e MEFSG e descreve a metodologia seguida na sua elaboração. É apresentada a formulação matemática geral para os elementos finitos utilizados no programa, bem como a descrição dos modelos reológicos considerados. Descrevem-se sumariamente todas as subrotinas utilizadas nos programas e apresentam-se as instruçõespara a construção dos ficheiros de dados e ficheiros auxiliares necessários para o funcionamento do programa. São ainda apresentadas as listagens dos programas.
Year: 1992
Author(s): Marcelino, J.
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Observação de barragens de aterro - Automatização do Tratamento da Informação
N/A
Year: 1986
Author(s): Marcelino, J.
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Colaboração no controle dos maciços terrosos da barragem do Mira 12º Relatório
N/A
Year: 1969
Author(s): Maranha das Neves, E.
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Outro
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Relato da visita de 22 de janeiro de 2024 à Linha do Oeste
Relato da visita de 22 de janeiro de 2024 à Linha do Oeste por parte do Departamento de Geotecnia
Year: 2024
Author(s): Pereira, C.; Brito, A.
Keywords: Terraplenagens
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Relato da visita de 26 de março de 2024 à Linha do Oeste
Relato da visita de 26 de março de 2024 à Linha do Oeste
Year: 2024
Author(s): Brito, A.; Pereira, C.
Keywords: Terraplenagens
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