Publicações

The installation of vibration-based structural health-monitoring systems relying in the study of natural frequencies to assess the condition of civil engineering structures is becoming more and more common. The extraction of these monitoring features can be achieved through automated operational modal analysis, combining output-only identification methods with cluster analyses, and comparing the identified modal properties with references, in a process known as modal tracking. However, changing environmental and operational conditions affect the dynamic behaviour of structures, disturbing the process of modal tracking, which may lead to the loss of important information and to misidentifications. In this context, this paperproposes a new methodology for modal tracking within the scope of automated operational modal analysis, especially prepared for scenarios with strong external influence on modal properties. A concrete arch dam with large variations of some natural frequencies is used as case study, and the proposed methodology is compared to a standard procedure using a quite unique monitoring data set continuously collected for 3 years.

Neste artigo apresenta-se a formulação e resultados da aplicação de dois modelos descontínuos tridimensionais que simulam a interação hidromecânica. Nestes modelos o comportamento mecânico é simulado de forma idêntica mas o comportamento hidráulico é simulado com duas abordagens diferentes. O primeiro modelo baseia-se numa formulação que admite o escoamento através de elementos planos de interface. O segundo modelo, que se propõe neste artigo, baseia-se numa discretização unidimensional, ocorrendo o escoamento através de elementos de canais. Os modelos hidromecânicos implementados no módulo computacional Parmac3D Fflow são verificados e validados através de exemplos simples, e o modelo proposto é calibrado de modo a serem obtidos, com os dois modelos, os mesmos valores de pressão e de caudal. Foi desenvolvido um modelo hidromecânico de um conjunto barragem/fundação, tendo em consideração a existência de cortina de impermeabilização e de sistema de drenagem na fundação. Salientam-se as vantagens do modelo proposto no estudo do comportamento hidromecânico de fundações de barragens.

Earthquake damage in historic masonry buildings is generally caused by the collapse of individual portions thatbecome detached form the structure and fail by overturning. These mechanisms are mainly governed by thediscrete nature and geometry of the block units. Analyses based on explicit micro-modelling in which each blockis considered separately are therefore of increasing importance. This paper offers a robust tool for the seismicassessment of masonry structures under either, quasi-static or dynamic loading. Algorithms for performing dynamicpulses and pushover analyses through the Discrete Element Method are developed and described, takinginto account the actual discrete nature and geometry of masonry. A numerical procedure is proposed thatautomatically detects the collapse mode and follows the evolution of the analysis until collapse. The implementedmethod is able to give a reliable estimate of the expected failure mechanism, providing the seismicacceleration required to trigger the motion and the ultimate displacement beyond which the collapse occurs.Finally, the implemented algorithms are applied to two case studies and the results are compared with thetraditional analysis based on rigid-block kinematics to outline the features and potentialities of the proposedapproach.

Conservation of the European-built heritage is nowadays closely related to interventions in masonry construction. Since a significant part of these structures are located in earthquake prone zones, designing protective measures that ensure their preservation requires the assessment of the associated seismic vulnerability and the understanding of their degradation mechanisms. However, due to the presence of discontinuities between its constituent elements, the numerical simulation of the non-linear response of masonry structures subjected to strong earthquakes is a cumbersome task, especially when performed using the traditional finite element method. As an alternative, the discrete element method is particularly suitable for the numerical analysis of such structures under large, damaging loads. By allowing discrete displacements/rotations of individual bodies, and by automatically recognising new contacts between bodies, while eliminating obsolete ones, this numerical approach can simulate the complete detachment of discrete bodies initially in contact.The present paper illustrates the use of the discrete element method to assess the seismic vulnerability of stone arches. A probabilistic approach allows to consider the variability of theseismic action and the uncertainties in the definition of the material properties. First, an unreinforced masonry arch is considered. Based on non-linear multi-directional incremental dynamic analyses, five damage states are proposed and the respective fragility curves are elaborated. Toimprove the arch

A seismic assessment study of two historical masonry arch bridges, with different geometries and spans, ispresented. The seismicity of the two locations was analyzed in order to define the seismic action to be applied.Artificial ground motion records were generated accordingly, and real ground motions were also used. The twonumerical models were created with a 3D discrete element code. The accuracy of the deformability of the blockmodels was verified by comparison with a finite element model. In situ measurements of the natural frequencieswere available for one of the bridges, providing further means for model calibration. Time domain dynamicanalyses were performed with each set of ground motions, allowing an evaluation of damage and failure modesunder seismic action. The shorter span bridge was found to withstand the regulatory records with minimumdamage. In contrast, the longer span bridge displayed a significant vulnerability to earthquake action. The studyshows that rigid block models have the ability to represent effectively the dynamic elastic response of the bridgesand can be calibrated by ambient vibration measurements. Furthermore, the discrete element models provide apowerful tool to investigate the nonlinear dynamic response and failure of these structures, which has to be basedon a comprehensive set of dynamic records.

Stability analyses of geotechnical structures in rock are traditionally performed using deterministic methods. In Europe, Eurocode7, introduced in the beginning of the 21st century, adopts limit state design and semi-probabilistic methods, using partial factors for the design of geotechnical structures. Meanwhile, reliability-based design, using probabilistic methods, is becoming more common in practical cases. The paper considers an intentionally simple case study?the analysis of a slope in a rock mass with one discontinuity, considered in a discrete way, forming a rock block to be stabilised by anchors?to compare the results obtained with the different methods. The objective is to calculate the force applied by the anchors so that the ultimate limit states of sliding of the rock block is verified. Deterministic-based design optimization considering both the traditional global safety factor approach and the partial factor approach following the Eurocode 7 are first applied. A reliability-based design optimization procedure?which takes geometrical and mechanical properties of the discontinuities as random variables?is then used, and the results are compared to the former ones. A discussion is presented concerning the consistency of the obtained results.

Civil engineering structures are generally supposed to have long operation life spans during which they aresubmitted to many factors, both environmentally and human-induced, that degrade their condition and performance,gradually leading to the occurrence of damages and malfunctions. Therefore, systems capable ofmonitoring and assessing structural performance automatically are highly desirable.In this context, this paper describes the vibration-based structural health monitoring of Baixo Sabor arch dam,in Portugal, detailing results from the several processing stages needed to achieve the ability to detect damage.Automated operational modal analysis is applied to the data obtained during the first three years of monitoring,after which environmental and operational conditions affecting modal properties are studied and their effectsminimised through the combined application of weighted regression models and principal components analysis.Finally, damages are simulated in a numerical model of the dam, and the results are used to test the ability ofdamage detection tools to find these anomalies.The present paper uses a quite unique set of experimental data to test for the first time the ability of avibration-based SHM system to identify realistic damages in an arch dam.

The paper investigates the effectiveness of two-dimensional Discrete Element Method as a tool forstructural analysis of arches provided with buttresses and backfill and strengthened with externallybonded reinforcement. Masonry vault and buttresses are modelled as an assembly of 2Drigid blocks interacting through non-linear contact joints, the backfill is discretized into deformableelastic-plastic triangular elements, while the reinforcement is modelled by means of trusselements bonded to the substrate through non-linear springs. A parametric analysis on theinfluence of material parameters and the effect of the discretization of the backfill is carriedout, and the outcome of different reinforcement systems, consisting of Steel Reinforced Groutapplied either at the intrados or at the extrados, are analysed. The comparison with experimentalfull-scale tests proved the ability of the numerical approach to capture hinges position, loadbearing capability, as well as the increase in deflection and load capacity provided by thereinforcement.

The uplift pressures change the stress state of the rock mass foundation in a coupled hydromechanical process and may compromise the dam stability. Consequently, dam safety regulations specify the maximum values of the hydraulic conductivity and uplift pressures that can usually only be fulfilled after the execution of seepage and uplift control measures. The design of waterproofing and drainage systems is still based on an equivalent continuum approach, even though rock mass foundations are discontinuous media. The analysis of the piezometric monitoring data of several Portuguese large concrete dam foundations reveals that uplift pressures are site-specific and may even vary considerably across a given site, which can be critical for the safety assessment. From the data gathered in several dams, a probabilistic model that can be seen as an a priori prediction model for uplift pressures is proposed. Considering the difficulty in classifying the geologic foundation conditions beneath each piezometer in existing dams, it is assumed that the data come from a mixture of two beta distributions, representing foundations with regular and unfavorable geologic conditions. This model is a significant improvement over available approaches and will be instrumental for the assessment of existing dams and the design of new dams.

The characterization of the dynamic behavior of an arch dam, and its evolutionthroughout the structure's lifetime, provides important data for the safetycontrol process. Forced vibration tests remain a reliable technique for this purpose.The Baixo Sabor dam is a 123 m high arch dam recently built in Portugal.Forced vibration tests were performed before and after the reservoir filling.Two techniques for forced vibration test are compared, discrete frequencyscanning, the standard methodology, and continuous frequency scanning (sinesweep), a new proposed methodology, which allowed faster results withoutloss of precision. For the interpretation of test results two numerical models ofthe dam-reservoir-foundation system were built, and calibrated with the experimentaldata. A good match of numerical and experimental results wasobtained for the six lowest frequencies and corresponding mode shapes.

Na presente comunicação é apresentado o estudo de caracterização dinâmica da barragem do Alto Ceira II recorrendo a métodos experimentais e numéricos. Foi efetuada a caraterização deste comportamento para as situações de albufeira vazia e cheia através da realização de ensaios de vibração forçada e da medição de ruído ambiente. A interpretação dos resultados das campanhas de ensaio e a estimação das características mecânicas médias do betão da barragem foi efetuada com o recurso a um modelo numérico calibrado com os resultados experimentais.

A determinação da resposta dinâmica das obras e o acompanhamento da evolução doseu comportamento durante as várias fases da vida é muito importante, estandoinserido nas atividades do controle de segurança estrutural. A realização de ensaiosde vibração forçada em barragens de betão para a determinação do comportamentodinâmico continua a ser uma das técnicas mais fiáveis nesta área. Nesta comunicaçãodescreve-se a metodologia de ensaio, incluindo os desenvolvimentos recentementeefetuados, e apresentam-se os resultados relativos a um caso de estudo, referente àcaraterização do comportamento dinâmico da barragem do Baixo Sabor. Foi desenvolvidoum modelo numérico para apoio na preparação do ensaio e interpretação dosresultados experimentais.

The characterization of the dynamic behavior of an arch dam, and its evolution throughout the structure

Dynamic fracture phenomena are studied employing low cost computational toolsbased on Finite Elements with Embedded strong discontinuities (E-FEM). Fracture nucleationand propagation are accounted for through the injection of discontinuous strain and displace-ment modes inside the finite elements. The Crack Path Field technique is employed to computethe trace of the strong discontinuity during fracture propagation.Unstable crack propagation and crack branching are observed upon increasing loadingrates. The variation in terms of crack pattern and energy dissipation is studied and a good cor-relation is found between the maximum experimental crack speed and maximum dissipation atthe onset of branching. Comparable results are obtained against simulations employing supra-elemental techniques, such as phase-field and gradient damage models, considering coarserdiscretizations which can differ by two orders of magnitude.

A determinação da resposta dinâmica das obras e o acompanhamento da evolução do seu comportamento durante as várias fases da vida é muito importante, estando inserido nas atividades do controle de segurança estrutural. A realização de ensaios de vibração forçada em barragens de betão, para a determinação das características dinâmicas, continua a ser uma das técnicas mais fiáveis nesta área. Nesta comunicação descreve-se a metodologia de ensaio, incluindo os desenvolvimentos recentemente efetuados, e apresentam-se os resultados relativos a um caso de estudo, referente à caracterização do comportamento dinâmico da barragem do Baixo Sabor. Descreve-se ainda o modelo numérico desenvolvido para apoio à preparação do ensaio e à interpretação dos resultados experimentais.

Modelos de análise com base em formulações de elementos discretos ou de elementos finitos com juntastêm sido propostos para a análise de estabilidade de barragens de betão para cenários que envolvem a rotura da fundação. Nesta comunicação é proposto um algoritmo de interação entre blocos deformáveis do tipo partícula esférica /superfície triangular. Para tal, o domínio interior de cada bloco é discretizado com partículas esféricas que interagem com as superfícies triangulares adotadas na discretização dos blocos vizinhos. A presentam-se várias análises de estabilidade/equilíbrio limite efetuadas com o modelo proposto,incluindo o exemplo da fundação de uma barragem abóbada. Verifica-se que os resultados obtidos, de interação partícula esférica/superfície triangular, são próximos dos obtidos com modelos que utilizam elementos discretos do tipo poliédrico, baseados em modelos de interação mais complexos.

Um modelo numérico para a análise de estruturas de betão armado deve incorporar ferramentas capazes de representar a formação e propagação de fendas, o efeito destas no comportamento global da estrutura, e a interação entre as armaduras e o betão. Para a modelação da fratura em materiais quase-frágeis têm sido utilizados modelos detalhados de partículas, inicialmente desenvolvidos para estudo do comportamento micro-mecânico de meios granulares, que têm em consideração a interação física entre as partículas e a influência da meso-estrutura do betão. Os modelos de partículas em 3D apresentam boa correlação com resultados experimentais de provetes de betões, nomeadamente em termos de resposta elástica, valores de pico, processo de fratura e localização da fratura.Nesta comunicação é apresentada a formulação explícita da modelação dos varões de aço em 3D através de elementos discretos com geometria cilíndrica. A incorporação de elementos de aço permite a aplicação do modelo de partículas à análise da fratura em estruturas de betão armado. Os elementos rígidos de geometria cilíndrica interagem com o betão, modelado por partículas esféricas, através de uma interface de contacto. O modelo é validado em ensaios de flexão em viga a três pontos, sem armaduras de esforço transverso. Os resultados numéricos obtidos no ensaio de flexão permitem verificar que o modelo proposto simula de forma correta o comportamento real, representando o processo de evolução da fratura e a relação carga-deslocamento.

Cracks propagating deep inside gravity dams can seriously affect theirstructural safety. Due to the potential catastrophic scenarios associated to the collapseof large concrete dams, it is a fundamental issue to realistically predict the eventualcrack profiles and the ultimate structural resistance associated to the failuremechanisms.This work investigates tensile crack propagation in concrete gravity dams by usingsome new recently developed numerical techniques (crack-path field and strain injectiontechniques) [1-3] associated to a Rankine-type plasticity model. The work carefullyaddresses aspects related to mesh independence (mesh bias and stress locking),robustness, and computational cost, which are the main issues in material failuremodeling. The numerical simulations presented in the paper show the advantages of thepresented approach.

Aborda-se a aplicação de modelos de elementos discretos a pontes de alvenaria, no quadro dos métodos disponíveis para a análise destas estruturas por modelos de meio descontínuo. Discutem-se as principais opções para a representação numérica, e as suas implicações práticas, tendo em vista principalmente estudos de avaliação da segurança.

En este trabajo se presenta un estudio del ensayo "Trapdoor" mediantemodelización numérica, empleando para ello dos modelos, uno continuo, construido conel código FLAC, y otro discreto, construido con el código PFC2D. Se incide en lasdiferencias de ambas metodologías a la hora de analizar un problema de rotura activa enel que la pérdida de material tiene un efecto significativo, como es el caso del ensayo"Trapdoor". Por un lado, el modelo continuo no representa fielmente la realidad delfenómeno, puesto que no considera la pérdida de material. Esto es especialmenteimportante en el caso de materiales con ángulos de dilatancia bajos en los que se produceuna evolución de la rotura a partir de un primer arco estable. Sin embargo, el modelodiscreto presenta importantes dificultades para asignar las propiedades macromecánicasdel material, lo cual limita notablemente la posibilidad de realizar estudios paramétricossobre las variables que caracterizan el material.

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 relatório apresenta-se, de forma sucinta, a descrição da atividade de investigação realizada no âmbito do projeto DEMRock6m do P2I/LNEC 2013-2020. Os resultados da atividade desenvolvida são analisados e avaliados em face dos objetivos inicialmente previstos.

Neste relatório apresenta-se, de forma sucinta, a descrição da atividade de investigação realizada no âmbito do projeto MEBAD do P2I/LNEC 2013-2020, no período 2016-2023. Os resultados da atividade são analisados e avaliados, em face dos objetivos previstos.

Neste relatório apresenta-se, de forma sucinta, a descrição da atividade de investigação realizada no âmbito do projeto RockGeoStat do P2I/LNEC 2013-2020. Os resultados da atividade desenvolvida são analisados e avaliados em face dos objetivos inicialmente previstos.

The main goal of this report is to present DamDamage3D1.0, a 3D finite element-based program for non-linear static analysis of arch dams, developed using MATLAB. The non-linear simulations are performed using a damage law and an iterative numerical method based on the stress-transfer technique, considering the redistribution of unbalanced forces in each iteration due to material damage. The concrete

The main goal of this report is to present DamDamage3D1.0, a 3D finite element-based program for non-linear static analysis of arch dams, developed using MATLAB. The non-linear simulations are performed using a damage law and an iterative numerical method based on the stress-transfer technique, considering the redistribution of unbalanced forces in each iteration due to material damage. The concrete

In this work we present the version 1.0 of the GDams2D 1.0 program developed for 2D analysis of gravity dams using the finite element method. This initial version of the program is prepared to analyze the structural behavior of gravity dams for static loads, considering linear-elastic behavior, and using Lagrange finite elements of 4 sides, with 9 nodal points. The GDams2D 1.0 program, developed in MATLAB, includes a module for automatic generation of meshes with a great level of refinement (generated from coarse meshes of quadrilaterals, with 4 nodal points at the vertices) and is designed for easy adaptation to non-linear analyzes, using stress-transfer modules such as those recently developed for the DamSlide3D and DamDamage3D programs. After a brief reference to the fundamentals of solid mechanics and to the simplified hypotheses of plane elasticity, the Fundamentals of the Finite Element Method (FEM) are presented, referring in particular the formulation of the four-node, linear and isoparametric, finite element (FE4nos), with two translation d.o.f per node, and the quadrangular FEs of 9 nodes (FE9nos) used in GDams2D 1.0. Based on some examples of application to simple 2D structures whose response is knownanalytically, the advantages of FEs are emphasized in relation to FE4nos and the verification and operability of GDams2D 1.0 is made using various discretizations. Finally, the case of a gravity dam (25 m high) is presented. The dam

The main objective of this work is the development and presentation of a three-dimensional finite element program, DamSlide3D, to study the behavior of gravity dams for scenarios of sliding through the dam-foundation interface. The DamSlide3D, developed using MATLAB, includes cube-type finite elements with 20 nodal points ("serendipity") and finite interface elements with 16 nodal points (joint elements). Initially, we present the fundamental equations of Solid Mechanics, referring to the main simplified hypotheses considered in the computationally implemented formulation, which is presented mathematically as a problem of boundary values using a displacement formulation. For the structure body and for the foundation, the hypothesis of isotropic materials with linear elastic behavior is assumed and for the interfaces the hypothesis of non-linear behavior is considered using the Mohr- Coulomb criterion. The DamSlide3D input data is provided in an excel file and includes structure geometry data, material properties, support conditions and load parameters. As output, the program graphically displays the stress field (principal stresses) and the displacement field (deformed structure). The program was verified throughout three numerical tests with known theoretical solutions. In these tests a simple structure was used, composed by a column discretized in 3DFE. At the contact surface between the column and the base (horizontal surface) it was considered an interface discretized using joint finite elements. A plane surface that crosses the column with a given slope is also considered, discretized using the same type of joint finite elements. In the first test, the field of elastic stresses at the base, due to self-weight (SW) and hydrostatic pressure (HP), was compared with the theoretical results. In the second test the nonlinear column response was studied for different values of thefriction angle at the inclined interface (in this test the structure is only submitted to SW). In the third test, for the main SW + HP loads, the stability of the column is studied for a variation of the friction angle, and for a variation of the water level. In these three numerical tests the results were always consistent with the theoretical solutions. Finally, as an example of application, a gravity dam structural behavior was analyzed considering the non-linear behavior in the dam-foundation interface. The dam was subjected to self-weight and hydrostatic pressure. A parametric study was developed in order to study the dam stability for differentvalues of water level and friction angle.

Neste relatório apresenta-se, de forma sucinta, a descrição da atividade de investigação realizada no âmbito do projeto CoMatFail até ao final de 2017. É feita a apreciação da atividade desenvolvida, nomeadamente quanto ao grau de cumprimento do plano de trabalhos, bem como dos objetivos específicos e dos indicadores de desempenho propostos na ficha de projeto. São ainda referidas as aplicações dos resultados da investigação em trabalhos contratados ao LNEC e as candidaturas a financiamento externo desenvolvidas no âmbito do projeto. Inclui-se em anexo a ficha do projeto atualizada, que contempla a revisão do plano de trabalhos.

Neste relatório apresenta-se de forma sucinta a descrição da atividade de investigação realizada no âmbito do projeto DEMRock6m no período 2016-2017. Os resultados da atividade são analisados e avaliados em face dos objetivos inicialmente previstos, sendo proposta uma revisão do plano de atividades para os próximos três anos.

Neste relatório apresenta-se, de forma sucinta, a descrição da atividade de investigação realizada no âmbito do projeto RockGeoStat no período 2016-2017. Os resultados da atividade são analisados e avaliados em face dos objetivos inicialmente previstos, sendo proposto um prolongamento do projeto até ao final de 2018.

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.