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
Info
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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Modelos de comportamento da barragem de Corumana em Moçambique
A barragem da Corumana é uma barragem de aterro zonado que dispõe de um sistema de observação em exploração há cerca de 20 anos. Os dispositivos desse sistema permitem medir as seguintes grandezas: nível de água na albufeira, deslocamentos superficiais, deslocamentos internos; caudais de infiltração, níveis piezométricos no interior do aterro e fundação e precipitação atmosférica. Após a apresentação e validação dos resultados do sistema de observação, que serviram de base à modelação matemática (estatística) do comportamento da obra, descreve-se a aplicação de modelos estatísticos a esses resultados. Os modelos obtidos são depois explorados para prever o comportamento da obra em diversos cenários e para estabelecer critérios de atenção e alerta a adotar na exploração futura.
Year: 2012
Number Pages:
15p.
Author(s): Portugal, J. C.; Marcelino, J.
Editor: Sociedade Portuguesa de Geotecnia
Keywords: Modelação estatística; Barragens de aterro
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Modelos de comportamento da barragem de Massingir em Moçambique
A barragem de Massingir, com quase 5 km de comprimento e uma altura máxima de 47 m é constituída por um aterro zonado e encontra-se em exploração há cerca de 30 anos. Esta barragem, uma das maiores de Moçambique, exibiu, logo após o início da exploração problemas de comportamento da fundação. A sua exploração ficou, então, condicionada e só após obras de reabilitação concluídas em2006, se iniciou a exploração normal da albufeira, mas sem a central de produção de energia instalada. Na sequência do re-enchimento, um importante acidente ao nível do funcionamento das descargas de fundo, voltou a condicionar a exploração da obra. Os dispositivos do sistema de observação permitem medir diversas grandezas, com base nas quais é possível estabelecer modelos de estatísticos que permitem aferir o seu comportamento sendo explorados para prever o comportamento da obra em diversos cenários e para estabelecer critérios de atenção e alerta a adotar na exploração futura.
Year: 2012
Number Pages:
15p.
Author(s): Marcelino, J.; Portugal, J. C.
Editor: Sociedade Portuguesa de Geotecnia
Keywords: Acidente; Modelação estatística; Barragens de aterro
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Modelos de comportamento da barragem dos Pequenos Libombos em Moçambique
A barragem dos Pequenos Libombos é uma barragem de aterro zonado que dispõe de um sistema de observação em exploração há cerca de 20 anos. Os dispositivos desse sistema permitem medir as seguintes grandezas: nível de água na albufeira, deslocamentos superficiais, deslocamentos internos,caudais de infiltração, níveis piezométricos no interior do aterro e fundação e precipitação atmosférica.Após a apresentação e validação dos resultados do sistema de observação, que serviram de base à modelação matemática (estatística) do comportamento da obra, descreve-se a aplicação de modelosestatísticos a esses resultados. Os modelos obtidos são depois explorados para prever o comportamento da obra em diversos cenários e para estabelecer critérios de atenção e alerta a adotar na exploração futura.
Year: 2012
Number Pages:
18p.
Author(s): Portugal, J. C.; Marcelino, J.
Editor: Sociedade Portuguesa de Geotecnia
Keywords: Modelação estatística; Barragens de aterro
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Monitoring the behaviour of Massingir dam in Mozambique
Massingir, an earth fill dam with nearly 5 km long and a maximum height of 47 m is the 2nd largest dam in Mozambique. The reservoir has a maximum storage capacity of about 2,800 hm³ and the flooded area, at the Normal Water Level (NWL), is 138 km². Dam construction took place between 1971 and 1977, but because of armed conflict and funding issues, the construction was incomplete, missing the installation of the spillway gates (six gates) and the hydro-power station.During the first filling in 1977 it exhibited serious behaviour problems on the foundation, namely because piping have occurred in large extensions of the right bank dike. Its exploitation was thus, limited, and only after the rehabilitation works completed in 2006, the normal exploitation of the reservoir begun, although still without the power house. The rehabilitation included the following tasks: i) partial treatment of the foundation, by grouting, ii) construction of a stabilizing berm downstream of the dam's right dike, iii) construction of relief wells along the right bank of the dike and the main valley; iv) the lift of 1 m of the crest elevation; v) construction of a concrete parapet on the crest; vi) rehabilitation of the rip-rap; vii) the installation of the spillway gates, viii) repair of hydro-mechanical equipments of the bottom discharges, ix) rehabilitation of the monitoring system and some other minor works.As a result of the re-filling, a major accident occurred at the exit of the bottom outlet discharges, reconditioning again the exploitation of the reservoir. Currently the dam is undergoing a new intervention to increase the capacity of the spillway flood discharges and to repair the bottom outlets exit. The dam has a monitoring system installed, from which several physical quantities are obtained, on the basis of which it is possible to establish statistical models used for assessing its behaviour and to predict its response for different scenarios. Furthermore, the models allow to establish criteria for attention and alert to adopt in future exploration.
Year: 2012
Number Pages:
12.
Author(s): Marcelino, J.; Portugal, J. C.
Keywords: Monitoring; Rehabilitation; Accident; Fill dam
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Odelouca Dam Construction: Numerical Analysis
Odelouca dam is an embankment dam, with 76 m height, recently constructed in the south of Portugal. It is zoned with a core consisting of colluvial and residual schist soil and with soil-rockfill mixtures making up the shells (weathered schist with a significant fraction of coarse sized particles).This paper presents a numerical analysis of Odelouca Dam`s construction. The material con-stants of the soil model used are determined from a comprehensive testing programme carried out in the Civil Engineering National Laboratory (LNEC) during the dam construction for the hydraulic and mechanical characterization of the materials used. Computational results are then compared between to the ones obtained from the dam monitoring system during the construction stage.
Year: 2012
Number Pages:
13.
Author(s): Brito, A.; Maranha, J. R.; Caldeira, L.
Keywords: Soil-rockfill mixtures; Embankments dams
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Odelouca dam Construction: Numerical analysis
Odelouca dam is an embankment dam, with 76 m height, recently constructed in the south of Portugal. It is zoned with a core consisting of colluvial and residual schist soil and with soil-rockfill mixtures making up the shells (weathered schist with a significant fraction of coarse sized particles). This paper presents a numerical analysis of Odelouca Dam`s construction. The material constants of the soil model used are determined from a comprehensive testing programme carried out in the Civil Engineering National Laboratory (LNEC) during the dam construction for the hydraulic and mechanical characterization of the materials used. Computational results are then compared between to the ones obtained from the dam monitoring system duringthe construction stage.
Year: 2012
Number Pages:
13p.
Author(s): Brito, A.; Maranha, J. R.; Caldeira, L.
Editor: 10th World congress on computacional mechanics
Keywords: soil-rockfill mixtures; soil constitutive models; embankments dams
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Using neural networks in earthfill dams emergency planning
Safety control of dams is made during the normal exploitation phase, with the support of monitoring data from the observation system and also from the visual inspections information and data, by comparing thereal and actual measurements with the values predicted by models of the expected dam behavior. The analysis of abnormal situations obliges to an intervention performed by a dam safety specialist who, facing the data from the observation system and the dam behavior model, will define the correspondent emergency level.This traditional approach, used on a daily basis for assessing dam safety, is adequate, but sometimes, it may delay significantly the actions to restore dam safety standards. In fact, a important time period canoccur, between the identification of an abnormal situation in the dam and the definition of the level of seriousness associated, as well as all the subsequent actions. The use of new technologies to help decision support and emergency planning can contribute to mitigate the effects of this disadvantage.The current paper presents a case study concerned with the use of an artificial neural network (ANN) in order to evaluate the behavior of an earthfill dam, Valtorno-Mourão Dam in Portugal. The developed modelallowed the identification of both normal and abnormal situations, establishing the correspondent dam alert levels.
Year: 2012
Number Pages:
12.
Author(s): Marcelino, J.; Viseu, T.; Tavares, J. L.
Keywords: Neural network; Observation system; Emergency planning; Dams
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Valtorno-Mourão Dam. Reinforcement of the foundation grout due to problems detected during the first filling
The Valtorno-Mourão dam in the municipality of Vila Flor is intended to create a reservoir with the total volume of 1.12 x106 m3 for water supply. The embankment has a crest length of 150 m and 32 m of maximum height. It as a homogeneous profile including a sub-vertical filter. The construction of the dam took place between July 2004 and January 2006. During the first filling, the comparison of the results of monitoring with the predictions from the Monitoring Plan lead to the conclusion that the dam was not having the expected behaviour, both for the amount of flow, which was roughly ten times higher than it was expected, and for the pore pressures measured in some piezometers. The Tras-os-Montes region in Portugal has normally severe conditions of water supply and the amount of loss in the dam was not compatible with normal supply to the populations. Given this scenario, it was decided to stop the first filling of the reservoir to allow the diagnosis of deficiencies. As a result, a new grouting treatment of the foundation was made, so that currently, the dam exhibits the desired behaviour. This paper seeks to describe the fundamental characteristics of the dam and foundation, some aspects of the construction, the diagnosis of disabilities, the treatment performed and, finally, the behaviour observed up to the date.
Year: 2012
Number Pages:
12.
Author(s): Marcelino, J.; Paixão, J. B.
Keywords: First filling; Reinforcement; Monitoring; Fill dam
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Applicability of Hilf`s Method to the Compaction Control of Soil-rock Mixtures
The employment of non traditional materials, such as soil-rock mixtures, in the construction of earthworks, for economical and environmental reasons, poses some new challenges to compaction techniques and their control. Usually, this kind of material results from the bulky rock extraction without explosives, and it can include some large size particles (greater than 0.5 m). Construction control of embankments built with soil-rock mixtures is still a subject that needs investigation, considering that it is necessary to extrapolate current test results, which have been reached by means of the truncation of the grain-size distribution curve, to the actual construction conditions. The behaviour of these materials depends of the relative fractions of theirs constituents, becoming closer to a soil, if the fine fraction is large with the coarser material scattered in it, or closer to a rockfill if the coarser particles are in contact with each other with the fines occupying the spaces between them. One of the control methods widely used in Portugal for embankments is the Hilf
Year: 2011
Number Pages:
13pp.
Author(s): Brito, A.; Caldeira, L.; Maranha, J. R.
Editor: CI-Premier Pte Ltd
Keywords: Odelouca dam; Compaction control.; Hilf`s method; Soil-rock mixtures
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Construction and first filling of Pinhão concrete face rockfill dam
The Pinhão dam is located in the municipality of Vila Pouca de Aguiar in the district of Vila Real, intersecting the Pinhão River. Its primary purpose is to create an urban water supply reservoir of 4.24 x106 m3.The dam has a profile of granite riprap with a concrete face as the impervious curtain. The maximum height of the dam is 22 m. Construction took place between September 2006 and March 2008 when, after authorisation was given by INAG, first filling started.This paper is intended to provide basic data on the dam and its construction phase and on the monitoring activities undertaken by the ATMAD in close collaboration with LNEC and INAG to ensure the safe control of this dam.
Year: 2011
Number Pages:
761-773pp.
Author(s): Marcelino, J.; Moras, M.; Ribeiro, S.
Keywords: Monitoring; First filling; 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 de Laboratórios de Engenharia da CPLP 2015/2016
Neste relatório apresentam-se as atividades realizadas no ano de 2015/2016 no âmbito do Programa deCapacitação de Laboratórios de Engenharia da CPLP, implementadas com recursos do Fundo Especial daCPLP, com a coordenação do Laboratório Nacional de Engenharia Civil (LNEC), na qualidade de instituiçãoProponente. Tem-se assim em vista fornecer ao Secretariado Executivo da CPLP elementos que permitam arealização 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
Year: 2017
Author(s): Antunes, M. L.; Portugal, J. C.; França Martins, M.
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Proposta de projeto: Programa de Capacitação de Laboratórios de Engenharia da CPLP 2016/2017
O presente projeto, designado por Programa de Capacitação de Laboratórios de Engenharia da CPLP, dásequência à cooperação que existe entre o Laboratório Nacional de Engenharia Civil (LNEC) de Portugal, osLaboratórios de Engenharia Civil dos Países Africanos de Língua Oficial Portuguesa (LABPALOP) e aAdministração Pública de Timor-Leste e foi definido durante a XXIX Reunião de Coordenação dos Convénios de Cooperação, em Díli, entre 2 e 6 de maio de 2016.
Year: 2016
Author(s): Antunes, M. L.; Portugal, J. C.; França Martins, M.
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Relatório de atividades intermédio: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP e Administração Pública de Timor-Leste 2015-2016
Apresenta-se o Relatório intermédio das ações de cooperação realizadas no âmbito do
Year: 2016
Author(s): Portugal, J. C.; França Martins, M.
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Proposta de projeto: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP e de Timor-Leste 2015
O presente projeto, designado por Programa de Capacitação dos Laboratórios de Engenharia dos PALOPe de Timor-Leste 2015, dá sequência à cooperação que existe entre o Laboratório Nacional de Engenharia Civil (LNEC) de Portugal, os Laboratórios de Engenharia Civil dos Países Africanos de Língua Oficial Portuguesa (LABPALOP) e a Administração Pública de Timor-Leste e foi definido durante a XXVII Reunião de Coordenação dos Convénios de Cooperação, na cidade de Luanda, nas instalações do Laboratório de Engenharia de Angola (LEA), entre 10 e 14 de março de 2014.
Year: 2015
Author(s): Antunes, M. L.; Portugal, J. C.; França Martins, M.
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Proposta de projeto:Programa de Capacitação de Laboratórios de Engenharia da CPLP 2015/2016
O presente projeto, designado por Programa de Capacitação de Laboratórios de Engenharia da CPLP, dásequência à cooperação que existe entre o Laboratório Nacional de Engenharia Civil (LNEC) de Portugal, osLaboratórios de Engenharia Civil dos Países Africanos de Língua Oficial Portuguesa (LABPALOP) e aAdministração Pública de Timor-Leste e foi definido durante a XXVIII Reunião de Coordenação dos Convénios de Cooperação, na cidade da Praia, nas instalações do Laboratório de Engenharia de Civil de Cabo Verde (LEC), entre 13 e 17 de abril de 2015
Year: 2015
Author(s): Antunes, M. L.; Portugal, J. C.; França Martins, M.
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Relatório de atividades intermédio: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP e Administração Pública de Timor-Leste 2014-2015
Apresenta-se o Relatório intermédio das ações de cooperação realizadas no âmbito do
Year: 2015
Author(s): Portugal, J. C.; França Martins, M.
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Relatório de atividades: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP e Administração Pública de Timor-Leste 2014-2015
Neste relatório apresentam-se as atividades realizadas no ano de 2014/2015 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: 2015
Author(s): Antunes, M. L.; Portugal, J. C.; França Martins, M.
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Relatório de atividades: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP e Administração Pública de Timor-Leste 2013
Neste relatório apresentam-se as atividades realizadas no ano de 2013 no âmbito do Programa de Capacitação 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 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.
Year: 2014
Author(s): Portugal, J. C.; França Martins, M.
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Proposta de projeto: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP e de Timor-Leste 2014
O presente projeto, designado por Programa de Capacitação dos Laboratórios de Engenharia dos PALOPe de Timor-Leste 2014, dá sequência à cooperação que existe entre o Laboratório Nacional de Engenharia Civil (LNEC) de Portugal e os Laboratórios de Engenharia Civil dos Países Africanos de Língua Oficial Portuguesa (LABPALOP) e foi definido durante a XXVI Reunião de Coordenação dos Convénios de Cooperação, na cidade de S. Tomé, nas instalações do Laboratório de Engenharia Civil de São Tomé e Príncipe (LECSTP), entre 15 e 18 de outubro de 2012.
Year: 2013
Author(s): Portugal, J. C.; França Martins, M.
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Relatório de atividades intermédio: Programa de Capacitação dos Laboratórios de Engenharia dos PALOP e Administração Pública de Timor-Leste 2013
Apresenta-se o Relatório intermédio das ações de cooperação realizadas no âmbito do
Year: 2013
Author(s): Portugal, J. C.; França Martins, M.
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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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