Publications

A series of very shallowearthquakes occurred in the late afternoon ofMay 11, 2011 near the city ofLorca and 55 kmfromMurcia in Spain. The main shock (Mw5.2) occurred at 17:47 (UTC), causing9 deaths and over 250 injured with widespread damage and panic.The strong motion generated by the event was recorded in the town of Lorca near the epicenter.It was a short duration record with peak ground acceleration higher than 0.37 g. In the vicinity ofthe recorded motion (360 m), there is an obelisk composed of 11 frustums resting on a 1-m-highfoundation with a total height of 5.71 m. The general motion observed after the event was of theorder of 1 cm (translation) for most interfaces, while at the upper two, the motionwas of rotationof 2° to 4° in the counterclockwise direction seen from above.In order to understand the behavior of such a structure, numerical simulations of the obeliskwereperformed with the discrete element code 3DEC, employing a rigid block model. The deformationis assumed to be concentrated at the joints between the blocks, governed in the linear range by thejoint stiffness parameters, in the normal and shear directions. In the nonlinear range, a purelyfrictional behavior is adopted, without tensile strength. An elastic joint was introduced at thebase of the model, simulating the deformability of the foundation. The global model deformabilitywas calibrated by means of in situ dynamic characterization.Dynamic analyses were performed, taking into account the large displacement effects that governthe block rocking motion, applying the recorded seismic motion in the 3 directions. Parametricstudies were undertaken to assess the influence of the various input parameters. The modelresults are compared with the observed permanent displacements of the structure.

It is known that rigid circular particle models proposed in the literature do not properly reproduce therock friction angle and the rock tensile strength to compressive strength ratio. A 2D rigid particle model is herepresented which tries to overcome these issues while keeping the simplicity and the reduced computational costs characteristic of circular particle models. A particle generation algorithm is adopted which generates polygonal shape particles based on the Laguerre

The hydrodynamic interaction between a solid (dam and foundation) and a fluid(reservoir) should be considered whenever the reservoir is present. A fluid displacement-basedformulation is presented, and two fluid elements are proposed: an 8-node fluid cubic elementsub-integrated (F8N-1GP), and an 8-node mixed discretization cubic element formed by twoindependent 5 tetrahedra overlay (F8N-MDE). A forced vibration analysis, and a maximumdesign earthquake equivalent loading, are carried out in two different dams. The performanceof the proposed fluid displacement-based finite elements is compared with the performanceobtained with the degenerated solid (DS) concept, and with the simplified Westergaard addedmass approach. It is shown that the SD approach can lead to erroneous pressure values at thefluid domain, and that the penalty term which prevents circulation modes needs to be consideredwhen less regular meshes are adopted in the fluid discretization.

Apresenta-se a formulação explícita de um modelo hidromecânico em pequenos deslocamentos, baseado numa tecnologia de elementos finitos de junta. O modelo hidromecânico proposto requer um esquema de pré-processamento robusto, de modo a garantir que os contactos entre os diversos blocos que representam o maciço rochoso de fundação e a barragem são somente aresta/aresta. A parte mecânica do modelo, apesar de limitada a pequenos deslocamentos, tem a vantagem de permitir uma representação rigorosa da distribuição de tensões ao longo das juntas. A parte hidráulica do modelo é perfeitamente compatível com a parte mecânica. O modelo hidromecânico é validado recorrendo a uma situação hipotética de uma barragem gravidade fundada num maciço com fraturação regular e a uma situação real de uma barragem em serviço, comparando os resultados com os obtidos com um modelo discreto em grandes deslocamentos. São também comparados os resultados de análises de estabilidade, concluindo-se que é possível avaliar a segurança ao deslizamento de barragens gravidade em betão recorrendo a modelos de interação em pequenos deslocamentos.

A numerical model for analysis of masonry gravity dams based on the Discrete Element Method is presented.The dam and the rock foundation are represented as block assemblies, using elementary 3- and 4-node blocks. Complex block shapes are obtained by assembling the elementary blocks into macroblocks,allowing the model to be applied in various situations ranging from equivalent continuum to fully discontinuumanalysis. A contact formulation was developed, which represents the interaction between macroblocksin terms of contacts established between elementary blocks, based on an accurate edge

The work presents two new numerical techniques devised for modeling propagating material failure, i.e. cracks in fracture mechanics or slip-lines in soil mechanics. The first one is termed crack-path-field technique and is conceived for the identification of the path of those cracks, or slip-lines, represented by strain-localization based solutions of the material failure problem. The second one is termed strain-injection, and consists of a procedure to insert, during specific stages of the simulation and in selected areas of the domain of analysis, goal oriented specific strain fields via mixed finite element formulations. In the approach, a first injection, of elemental constant strain modes (CSM) in quadrilaterals, is used, in combination of the crack-path-field technique, for obtaining reliable information that anticipates the position of the crack-path. Based on this information, in a subsequent stage, a discontinuous displacement mode (DDM) is efficiently injected, ensuring the required continuity of the crack-path across sides of contiguous elements. Combination of both techniques results in an efficient and robust procedure based on the staggered resolution of the crack-path-field and the mechanical failure problems. It provides the classical advantages of the

The underground structures of the Venda NovaII reversible hydroelectric power scheme present features that make it an interesting case study. Worthy of mention are the inclination and length of the unlined pressure tunnel, the high water head and the great depth of the powerhouse cavern. In projects of this type, the main effect ofthe internal water pressure in the pressure tunnel is the establishment of seepage from the tunnel into the rock mass, which can reach the adits and the powerhouse cavern.This seepage is influenced by several factors, such as the geometry of the underground openings, the rock massproperties

Ground vibration is the most important environmental effect of blasting, and tools for its understanding and control are a prime necessity for the excavation of tunnels and caverns in hard ground. This paper contributes to an improved understanding of the way waves travel in the ground, particularly when there are excavations in the path of propagation, while also enhancing existing numerical models to better simulate that behaviour and thus provide better means to address underground vibration impacts. To this purpose, twenty low intensity blast between neighbour tunnels of an underground complex were performed, followed by a numerical study of the test. The test and simulation showed that, contrary to what is implied in semi-empirical attenuation laws, factors like the propagation path or local amplification can be more important than instant explosive weight and distance to blast.

tThis paper presents the development of a three dimensional computational model, based on the DiscreteElement Method (DEM), which was used to investigate the effect of the angle of skew on the load carryingcapacity of twenty-eight different in geometry single span stone masonry arches. Each stone of the archwas represented as a distinct block. Mortar joints were modelled as zero thickness interfaces which canopen and close depending on the magnitude and direction of the stresses applied to them. The variablesinvestigated were the arch span, the span: rise ratio and the skew angle. At each arch, a full width verticalline load was applied incrementally to the extrados at quarter span until collapse. At each load increment,the crack development and vertical deflection profile was recorded. The results compared with similar

Purpose - The rigid spherical particle models proposed in the literature for modeling fracture in rock have some difficulties in reproducing both the observed macroscopic hard rock triaxial failure enveloped and compressive to tensile strength ratio. With the purpose of obtaining a better agreement with the experimental behaviour, a 3D generalized rigid particle contact model based on a multiple contact point formulation is presented which allows moment transmission and includes in a straightforward manner the effect of friction at the contact level.Design/methodology/approach

Micromechanical modelling based on the Discrete Element Method (DEM) has been widely used to investigate asphalt behaviour due to its ability to represent an irregular microstructure with variable-sized aggregates, bitumen and voids. The 3D rigid particle models with randomly distributed spherical particles and adopting elastic and/or simple viscoelastic models at the contacts are the standard approach, however, in recent years, a significant research effort is noted to incorporate real particle morphologies in the numerical models.In this study, a previously developed 3D DEM model of asphalt employing a generalised Kelvin contact model formulation for the viscoelastic contacts is further improved with realistic particle shapes representing the coarse aggregates. A digital library of aggregate shapes was created from the X-ray computed tomography (CT) scan of an asphalt specimen, using an adaptive image-processing method to separate the aggregates in the CT images and the Delaunay triangulation method to define the aggregate 3D surface model. Several virtual aggregates with different sizes were selected from the library to represent the coarse aggregate gradation of the modelled 3D DEM asphalt specimen. Each virtual aggregate is discretized with smaller spherical particles and its deformability is taken into account through the inner particle contacts. The numerical asphalt specimens with realistic particle shapes were submitted to uniaxial tension-compression cyclic tests to determine the stiffness properties, and the results were compared with those of the numerical specimens with all constituents represented by single spherical rigid particles. As shown, the proposed methodology greatly enhances the 3D DEM model's ability to simulate the asphalt behaviour.

A avaliação da resposta dinâmica das obras e o acompanhamento da evolução do seu comportamento durante as várias fases da vida é muito importante, estando inserida nas atividades do controle de segurança estrutural. A barragem do Baixo Sabor possui sistemas de monitorização dinâmica em continuo e sísmica, tendo sido realizados dois ensaios de vibração forçada para duas cotas de albufeira. Foram desenvolvidos modelos numéricos incorporando o conjunto barragem-fundação-albufeira, calibrados com os resultados experimentais. Apresentam-se os resultados dos modelos numéricos desenvolvidos para vários níveis da albufeira comparando com a monitorização, durante a operação normal e a ocorrência de eventos sísmicos, verificando-se uma boa concordância.

The Baixo Sabor dam is a 123 meters high concrete arch dam located in the north of Portu-gal. After the performance of a forced vibration test, a quite unique experimental programme was initiated in the dam during the first filling of the reservoir, with the installation of a con-tinuous dynamic monitoring system in December 2015. The implementation of such a system aimed to study the evolution of the dam

Stability analysis of rock slopes is an exercise that poses a variety of challenges to arock engineer. Field information is often lacking and subjective modelling of the rock mass isrequired. Expert judgment also influences the quantification of the targeted safety level, reflectingthe confidence of the designer in his own assumptions and hypothesis. With the introduction of theEN1997 in Europe, structural reliability concepts were brought to the design of geotechnicalstructures, now also including rock masses after its current revision. Yet, fully-probabilistic methodsare still considered valid alternatives to the partial safety method recommended there. Understandinghow to address rock engineering problems from a probabilistic perspective becomes essential tomove beyond the traditional practice. In this study, a simple problem relating to the stability of a rockslope is explored. Limit states for foreseeable failure mechanisms are defined and the systemreliability problem is formulated and solved.

O artigo considera um caso de estudo intencionalmente simples

The Castelo do Bode hydraulic tunnel is part of the Lisbon water supply system. During its con-struction a monitoring system was implemented, aiming at monitoring the behaviour of the con-crete tunnel lining and of the surrounding rock mass, and including visual inspections.This work presents the monitoring system and introduces the relevant aspects of the analysis of the tunnel lining behaviour, based on the observed structural response to the imposed actions, namely the hydrostatic internal and external pressures, thermal variations, contact pressures and time effects. Two types of models are used: i) a structural model, based on axisymmetric analyt-ical solutions of concentric permeable rings allows setting a reference situation from which it is possible, by comparison, to assess the tunnel

This paper presents the analysis, interpretation and prediction of the structural behavior of CahoraBassa dam, which concrete is affected by a moderate ongoing swelling process, of the alkali-silica (ASR)type. To estimate the evolution of the dam

Uma das técnicas de reforço usadas na reabilitação e reforço estrutural de paredes deedifícios antigos em alvenaria de pedra é o confinamento transversal simples através deelementos de aço fixados perpendicularmente à parede. Neste estudo apresenta-se osresultados numéricos da simulação de ensaios de compressão simples de paredes reforçadoscom esta técnica, utilizando um modelo de partículas 2D (MP-2D). Os estudos numéricosapresentados demonstram que os modelos do tipo MP-2D apresentam uma boa concordânciacom ensaios experimentais, nomeadamente no acréscimo do valor máximo em compressãosimples. Demonstra-se assim, que os modelos MP-2D podem ser adotados nodesenvolvimento de soluções de reforço deste tipo, nomeadamente na definição dascaracterísticas das barras, posicionamento e quantificação.

This paper presents the study of the influence of temperature and stress field seasonal variations in thedevelopment of concrete swelling in dams, considering the case study of Covão do Meio arch dam, inPortugal, which concrete is affected by a moderate ongoing swelling process, of the alkali-silica (ASR)type, and which reservoir empties every year in the dry season.In a first step, a three-dimensional model of the dam and of the rock mass foundation, solved by thefinite element method, was used for the interpretation of the dam

A barragem do Covão do Meio, localizada na vertente sul da serra da Estrela a uma altitudede 1650 m, é uma estrutura em abóbada com 28 m de altura máxima cujo betão está afetadopor reações expansivas de moderada magnitude, do tipo álcalis-sílica.Para interpretar o comportamento observado da barragem e os efeitos estruturais dasexpansões, desenvolveram-se modelos de elementos finitos da obra, nas vertentes estruturale térmica, tendo os resultados da modelação apresentado uma boa concordância comresultados da observação contínua. Numa segunda fase foi feita a previsão docomportamento da obra para um horizonte temporal de 20 anos, tendo em conta dois cenários,um otimista, em que as expansões estabilizam a médio prazo com valores finais moderados,e um pessimista, em que o potencial remanescente de expansão é mais significativo.

Masonry is a combination of units such as stones, bricks or blocks usually laid in a cementitious or limemortar. It is probably the oldest material used in construction and has proven to be both simple to buildand durable. Over the years, existing masonry constructions have inevitably suffered damage with time.Earthquakes, soil settlements, material degradation and lack of maintenance are the main reasons forthat. Careful and periodic assessment of such structures is necessary in order to evaluate their structuralcapacity and safety levels. However, performing the structural analysis of masonry construction is notan easy task. A review is presented of the main models based on the discrete element method and the available related numerical techniques that have been proposed for the analysis of masonry. The essential assumptions adopted by these models and numerical implementation issues are discussed. Differences between available models are illustrated by applications to various masonry problems including static and dynamic analysis of masonry arch bridges, walls, vaults, domes and ancient colonnades.This book is composed of 17 chapters authored/co-authored by 25 outstanding researchers from 11countries (Canada, France, Greece, Hungary, Iran,Italy, Mexico, Norway, Portugal, UK, USA), whichwere reviewed by 60 referees.

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This chapter consists of two parts. First a general overview is given: the exact definition of the Discrete Element Method is provided, and the main types of existing models are introduced; then the theoretical fundaments of the most important approaches available today for masonry analysis are given. The second part of the chapter focuses on 3DEC, the most widespread commercial DEM code for masonry analysis. This second part begins with a theoretical overview. Application issues for masonry structures are then considered (block material behaviour, contact representation, structural elements like cables or bars etc.). Among the practical examples arches, barrel vaults, walls, coloumns and complete structures (like houses) are presented, including the issues of quasi-static versus dynamic analysis and of block fracture as well. The readers can find helpful advice on how to simulate their own problems most effectively.

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Discrete element models have become a major tool for masonry analysis, allowing a suitable representation of its discontinuous nature and marked nonlinear behaviour. The chapter reviews the fundamental assumptions of the main DEM formulations available. It focuses more specifically on the widely used UDEC and 3DEC codes, explaining their relation with the other approaches, and the most relevant issues arising in their application to masonry. Applications to the main types of structures are reviewed, considering both static and dynamic analyses. Recent research providing comparisons of the numerical models with experimental and field data is particularly covered. The discussion of the different examples is aimed at clarifying the key capabilities of DEM and demonstrating the most effective ways of using it in a variety of masonry analysis situations.

This chapter is focused on the Portuguese experience on the developmentand exploration of systems for continuously monitoring dam vibrations, usingaccelerometers. The pioneer system for seismic and structural health monitoring(SSHM) installed in Cabril dam (the highest Portuguese arch dam: 132 m high) isdescribed in detail. The design of this system was the result of a long-term LNECresearch program, still ongoing. These monitoring systems should include softwaredeveloped to automatically perform the analysis of collected data, including theautomatic comparison with numerical results from 3DFE models. In view of thegood results obtained with the system in operation in Cabril dam since 2008, similarsystems have been installed in other large dams in Portugal, particularly in recentlybuilt dams. Finally, Baixo Sabor dam is presented as an example of a new Portuguesedam with a complete SSHM system, in operation since 2015. Themain experimentalresults obtained for both dams are shown, namely the evolution of natural frequenciesover time, mode shapes and the measured seismic response to earthquake events.

Para verificação do cumprimento das exigências de segurança das barragens,tanto relativamente à funcionalidade (cenários correntes), como em relação àsegurança ao colapso (cenários de rotura), é essencial utilizar modelos de simulação oude interpretação (no caso de obras existentes) do seu comportamento. Estes modelossão idealizações (simplificações) da realidade, tanto no que diz respeito às acções(modelos das acções), como no que respeita à componente estrutural (modelos estruturais).A solução destes modelos, através de adequados métodos de análise, quantificaparâmetros da resposta das estruturas que permitem avaliar a sua segurança, utilizandocritérios de segurança previamente definidos.A validação destes modelos pode ser feita, no caso de cenários correntes,através da sua comparação com os resultados da observação do comportamento debarragens. No caso de cenários de rotura, não existe muita experiência de comparaçãodestes resultados com situações reais: é pequeno o número de acidentes ocorrido e,mesmo nestes, o volume de informação é reduzido. Desta forma, o recurso a métodosexperimentais, para o estudo de cenários de rotura, tem uma importância acrescida.Assim o principal objectivo deste trabalho é contribuir para melhorar a capacidade deavaliação da segurança de barragens de betão envolvendo cenários de rotura pela fundação.Neste trabalho desenvolveram-se dois ensaios experimentais em modelosfísicos: um primeiro envolvendo uma barragem abóbada, para o estudo de cenários derotura da fundação para acções estáticas; e um segundo de uma barragem gravidadeensaiado em mesa sísmica, com vista a estudar a rotura pela fundação para acçõesdinâmicas.A previsão e interpretação dos ensaios foram efectuadas com modelosmatemáticos adequados, que permitiram a sua validação e posterior utilização no estudode outros cenários.

Neste trabalho apresenta-se o sistema para monitorização em contínuo do comportamento dinâmico da barragem do Cabril que foi instalado em 2008, pelo LNEC e pela EDP, referindo alguns dos principais resultados que têm sido obtidos a partir da análise dos dados recolhidos, quer sob excitação ambiente/operacional, quer sob ações sísmicas. Salienta-se a importância do desenvolvimento do software para tratamento, análise e gestão automática dos dados e apresentam-se os programas que têm vindo a ser desenvolvidos no LNEC, em MATLAB, para apoio a este tipo de sistemas, nomeadamente programas de identificação modal (Modal_ID2.0 e Modal_ID_Auto2.0) e programas de elementos finitos tridimensionais para análise do comportamento dinâmico de sistemas barragem-fundação-albufeira (DamDySSA2.0).

This document presents the research plan for the doctoral thesis of LNEC's Junior Research Fellow Margarida Espada. This work, to be submitted to the Faculty of Engineering of the University of Porto (FEUP), will be developed in the Modelling and Rock Mechanics Unit of the Concrete Dams Department, and it is part of the on-going P2I research project DEMRock6m. This work aims at developing more efficient methodologies to perform safety studies and seismic analysis of rock engineering structures, based on discrete element models and in the integrated use of probabilistic models for the geometric and shear strength parameters and for the water pressures in rock discontinuities. This will allow a more realistic definition of the rock mass in discrete element models and an adequate identification of the potential failure mechanisms.

Neste relatório é apresentado o método de Euler para calcular as órbitas do sistema n-corpos,por exemplo, o dos planetas do sistema Solar, tendo em conta a propagação das forçasgravíticas entre o Sol e os planetas e entre os planetas entre si. Apenas requer como dadosiniciais uma observação anterior das órbitas em termos de posição e velocidade. A correcçãoda interacção entre planetas não é suavizada, o que se justifica pelos seus valores. A correcçãorelativista é importante.

As equações de Navier-Stokes são equações de derivadas parciais. As incógnitas nocaso de incompressibilidade consistem no campo de velocidades. As pressões numa 1ªaproximação resultam de um equilíbrio estático.A principal causa de problemas relacionados com a solução destas equações é devida àparcela das acelerações convectivas que está na origem da turbulência.Pesando estas equações e integrando duas vezes por partes obtém-se uma forma fracadestas equações.Em problemas 3D as variáveis independentes são 3 espaciais e 1 temporal. Admite-seque o campo de velocidades pode ser desenvolvido em série de distribuições de Delta deDirac espaciais e suas derivadas com coeficientes funções do tempo. Com funções deteste polinomiais obtém-se a formulação distribucional proposta das equações deNavier-Stokes.

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O objectivo deste relatório é o estudo da matemática aplicada à solução de problemasfísicos de propagação de ondas esféricas com operador espacial biharmónico,consideradas quânticas.As técnicas matemáticas usadas incluem a transformada de Laplace da função de ondaf e o cálculo de sua inversa tal como sugerida por Pipes e Harvill.O método matemático usado para descrever as ondas esféricas quânticas é compequenas adaptações o método causal não-linear descrito por Croca.

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A análise do comportamento de barragens de betão com base em modelos de elementos finitos tridimensionais exige a definição da discretização a adoptar para o conjunto barragem-fundação, ou barragem-fundação-albufeira. A realização desta tarefa sem o recurso a programas de geração automática é muito dispendiosa pelo que tem vindo a ser desenvolvido no NMMF um módulo computacional para geração automática de malhas de elementos finitos tridimensionais especialmente adaptado para a geração de malhas tridimensionais de barragens abóbada. Inicialmente desenvolvido em FORTRAN, o referido módulo computacional para geração de malhas de elementos finitos tridimensionais tem vindo a ser objecto de diversos melhoramentos, os mais recentes centrados ao nível da interface com o utilizador. Assim, apresenta-se neste relatório o módulo computacional

This document presents a back analysis procedure for identification of the elastic parameters of transversely isotropic rock cores, containing an overcoring triaxial strain probe, from the strains measured during a biaxial test. A three-dimensional finite element model was developed to simulate the biaxial test on the overcored rock specimen and to compute the strains at the location of the strain gauges. Different optimisation algorithms were tested and the most suitable one was selected. The back analysis procedure was tested for identification of the five elastic parameters and the two orientation angles that characterise a transversely isotropic rock core. In spite that, with the developed methodology, convergence was reached and all those parameters could be identified, sensitivity analyses demonstrated that the results obtained were not stable and therefore they were not reliable. By introducing constrains based on common practice and previous experience, a stable and robust methodology was achieved: the three elastic parameters, E1, E2 and ?2, are reliably identified using the value of G2 calculated with Saint-Venant’s expression and a fixed value of ?1, while the orientation parameters are obtained from observation of overcored rock. Analysis of the results shows that application of this methodology represents an enormous step forward when compared with the traditional use of isotropy. Besides, the methodology is general and can also be used with other types of overcoring equipment. The five elastic parameters and the two orientation angles obtained can then be used, together with the overcoring strains, to compute the complete in situ state of stress.

This document presents the work developed by the PhD student Margarida Espada in the scope of the course unit Risk Analysis in Geotechnical Works of the Doctoral Program in Civil Engineering of the Faculty of Engineering of the University of Porto (FEUP). This work presents a reliability analysis, using the response surface method (RSM), for the case study of the left bank excavation slopes of the Baihetan arch dam foundation, which is one of the case studies of Margarida Espada's PhD thesis. The aim was to approximate an implicit limit state function by computing safety factors, using a discrete element model of the Baihetan left bank developed in 3DEC software, where the shear strength parameters of two important rock discontinuities were considered as random variables. The probability of failure was then obtained through an iterative process, using approximation methods. This work presents the 3DEC model developed to analyse the stability conditions in the Baihetan left bank and the results of the reliability analysis.

O problema da solução das equações de Navier Stokes é abordado neste trabalhopropondo-se uma técnica de representação das incógnitas deslocamentos e pressõesvariáveis no espaço e no tempo em série de Delta de Dirac e suas derivadas no tempocujos coeficientes se determinam com base na solução de sistemas de equaçõesdiferenciais definidos no espaço (problema com três variáveis espaciais independentesque pode ser estudado pelo método de Monge).

Neste relatório apresentam-se as equações básicas da elastodinâmica linear, as soluçõesfundamentais e o teorema da representação no domínio de tempo e de frequência.Para movimentos finitos de casca formula-se o teorema dos trabalhos virtuais e a suaimplementação pelo método dos elementos finitos.

Neste relatório apresentam-se os principais aspectos da modelação sísmica de barragensabóbada. Assim propõe-se: modelos numéricos de geração de sismos por uma falha; aforma como o sismo actua na barragem; modelos para estudar a influência da albufeirana vibração do conjunto; métodos para solução das equações do movimento; e novasformulações de elementos finitos para o problema estrutural.

In pressure tunnels and shafts, in addition to the mechanical effect that excavation has on the rock mass and the disturbance that it introduces in the water flow, also the contained water can interact from the mechanical and hydraulic points of view with the rock mass. Seepage in fractured rock masses is dominated by the flow that takes place through the joints, and this is highly d(;pendent on their properties, namely aperture and roughness. Joint aperture, in tum, i::; very sensitive to stress changes. Special attention must therefore be paid to the joints in hydromechanical analyses. In this report are presented some studies that were carried out for the hydromechanical characterization of joints of the Alto Lindoso rock mass and numerical simulations of the hydromechanical behaviour of two selected sections of the high pressure circuit.