António Cardoso

University of Porto | UP · Departamento de Engenharia Civil

As soluções de fundações indiretas são frequentemente utilizadas em edifícios localizados em cenários geotécnicos desfavoráveis. A cravação de estacas é uma possibilidade interessante para a sua materialização, com vantagens do ponto de vista económico e técnico. Contudo, é necessário assegurar que as questões ambientais, nomeadamente as vibrações...

Impact pile driving is one interesting possibility to install deep foundations from the economic and technical point of view. However, it is necessary to ensure that the ambiental drawbacks, namely ground-borne vibrations, are adequately met. In that way, the authors propose an axisymmetric FEM-PML approach, where the non-linear behavior of the soi...

Analisa-se as principais soluções construtivas usadas no suporte de grandes escavações em meio urbano e situa-se no tempo o seu desenvolvimento. Mostra-se como às técnicas construtivas estão associados sistemas estruturais que, ao longo do tempo, foram sendo sucessivamente mais complexos, permitindo a execução de escavações em situações geotécnicas...

The use of pile driving techniques in urban environments demands accurate methods to predict and mitigate the potential discomfort of residents of neighboring buildings. In this context, a numerical model to predict ground-borne noise and vibrations in buildings induced by pile driving is proposed in the present paper. The model is based on a sub-s...

Pile driving is an effective constructive method for foundations in shallow soil layers with low bearing capacity. Its installation generates the propagation of vibration through the ground that can damage structures or disturb people in the vicinity of the pile driving, requiring a significant level of knowledge from the scientific and technical c...

Pile driving is one of the methods most used for foundations constructions when dealing with shallow soil layers with low bearing capacity. This pile installation in urban environments requires significant level of knowledge from the scientific and technical communities about the phenomena of generation and propagation of vibrations with emphasis o...

This study presents the numerical modelling of a load-volume road pavement section with bitumen emulsion-stabilised base courses. The base courses used natural and construction and demolition aggregates. A 3D finite difference model was used to determine the peak responses of the pavement sections when subjected to loads. Three nonlinear models wer...

A procedure for analyzing the shakedown limit load of non-ballasted railway tracks is presented. The shakedown theory is formulated based in the Melan's shakedown lower bound theorem for frictional soils, i.e., adopting the Mohr-Coulomb yielding criteria. The shakedown analysis is enlarged regarding to solutions presented by other authors by incorp...

O Círculo Meridiano de Espelho (C.M.E.) é um instrumento que permite determinar a Hora, ao centésimo de segundo, através da observação astronómica. Trata-se de um instrumento que foi construído nos anos cinquenta no Observatório Astronómico da Universidade do Porto (Faculdade de Ciências) e que funcionou até meados dos anos oitenta, altura em que f...

A engenharia geotécnica é um dos primeiros domínios técnico-científicos a intervir em qualquer projeto de infraestruturas ou de desenvolvimento urbano, sendo, muitas vezes, o mais importante. No decurso dos tempos muitas inovações metodológicas, analíticas, numéricas e tecnológicas foram sendo descobertas e utilizadas nas investigações de campo e d...

A engenharia geotécnica é um dos primeiros domínios técnico-científicos a intervir em qualquer projeto de infraestruturas ou de desenvolvimento urbano, sendo, muitas vezes, o mais importante. No decurso dos tempos muitas inovações metodológicas, analíticas, numéricas e tecnológicas foram sendo descobertas e utilizadas nas investigações de campo e d...

The present paper focuses on the experimental validation of a numerical approach previously proposed by the authors for the prediction of vibrations inside buildings due to railway traffic in tunnels. The numerical model is based on the concept of dynamic substructuring and is composed by three autonomous models to simulate the following main parts...

A engenharia geotécnica é um dos primeiros domínios técnico-científicos a intervir em qualquer projeto de infraestruturas ou de desenvolvimento urbano, sendo, muitas vezes, o mais importante. No decurso dos tempos muitas inovações metodológicas, analíticas, numéricas e tecnológicas foram sendo descobertas e utilizadas nas investigações de campo e d...

Geotechnical engineering is one of the first technical and scientific fields to intervene in any infrastructure or urban development project and, in many cases, it is the most important. In the course of time many methodological, analytical, numerical and technological innovations have been discovered and used both in field and in laboratory invest...

In this paper a numerical study about the influence of soil stiffness on the assessment of vibrations induced by railway traffic in tunnels is presented. A comprehensive numerical model is used to achieve the lumped objective, where the source of vibration (train–track interaction), the propagation of vibrations (tunnel-ground system) and their rec...

The renewal imposed by the Eurocodes regarding the methodologies of safety evaluation requires a statistical analysis of the variability of ground geotechnical parameters. However, the studies published in the reviewed literature do not cover the typical materials from the northeast region of Portugal—residual soils from granite—to which a strong h...

In this paper, a numerical approach for the prediction of vibrations induced in buildings due to railway traffic in tunnel is proposed. The numerical method is based on a sub-structuring approach, where the train is simulated by a multi-body model; the track–tunnel–ground system is modeled by a 2.5D FEM–PML approach; and the building by resource to...

The dynamic amplification effects of the response due to a moving load on the surface of an elastic solid has been object of research for more than a century. However, if in the beginning of the last century the problem had only theoretical interest, this is no longer true. Indeed, the recent advancements in the rolling stock, which can now reach s...

This chapter is about the vibrations induced by railway traffic, comprising theprediction models, its experimental validation and its application on the analysis ofmitigation measures. Due to the specific aspects of this kind of problems, where verylarge domains need to be considered, a 2.5D approach is adopted in the developing of thenumerical mod...

The simulation and study of problems related with vibrations induced by railwaytraffic in tunnels is a difficult and complex task. The semi-infinitive character of thedomain surrounding the tunnel associated to the 3-dimensional characteristics of theproblem is one of the major causes of that complexity. An efficient and accurate solutionfor the si...

This paper presents a numerical study developed in order to understand the dynamic behavior of ballasted tracks with mats including the train–track–ground interaction. In order to achieve that goal, a case study is modeled by a 2.5D FEM–BEM formulation. A comprehensive approach is presented and the effects of the mat stiffness and location in depth...

This paper presents a study developed in order to identify the influence and relevance of the mechanical properties of the train in the prediction of vibrations induced by passenger railway traffic. Based on experimental data and numerical simulation, a discussion about the influence of the modelling strategy adopted for the train simulation is per...

The first part of the paper includes a brief presentation of a 2.5 D FEM-BEM model, developed by the authors, which is able to lead with problems of vibrations induced by traffic including the train–track dynamic interaction. Then a global description of a test site developed on a stretch of the Portuguese railway network is presented. In that test...

The vertical stability of anchored concrete soldier-pile walls is highly influenced by the complexity of the interaction between the different parts of the structure, i.e., wall, anchors, and supported soil mass. The problem is analyzed using upper bound limit analysis through published solutions and proposed closed-form equations. A comparison is...

The main objectives of this paper are the evaluation of the relevance of the non-linear behaviour of the soil on the track response and the validation of a methodology, which includes these effects through an equivalent linear analysis. The proposed numerical model is based on 2.5D finite/infinite elements method, coupled with an iterative procedur...

Tropical residual clays with a highly porous structure react to the stress changes induced by tunneling in such a way that surface settlements can be larger than crown-level settlements along a tunnel axis. This behavior, which is not readily simulated by most numerical analyses, was also observed in the Paraiso tunnel, built for the São Paulo Metr...

A parametric study of an embankment on soft soils reinforced with stone columns is performed using a computer program based on the finite element method. The cylindrical unit cell formulation is used by modeling one column and its surrounding soft soil with confined axisymmetric behaviour. The computer program incorporates the Biot consolidation th...

The paper presents the design and construction of an elliptical excavation for Porto Light Metro. Due to its original shape the solution took full advantage of the arch effect in the ground, adapting the Sequential Excavation Method to the vertical direction and achieving a novel, light and economic solution. In a first phase, the paper describes t...

A previous paper studied the stability of soldier-pile walls in clay under vertical loading using upper bound analyses. A classical Tresca yield criterion was assumed in that analysis. This paper extends that study by considering a tension truncated Tresca yield criterion in an upper bound numerical analysis of the problem. It shows that assuming z...

In order to simulate pull – out in FLAC3D, the fibreglass nail is pulled with a small constant velocity, while the wall where the cable is inserted is kept fixed. Plots that relate pull force and cable displacement are created. All plots obtained show a similar behaviour, with the cable being pulled out of the borehole after a peak force is reached...

O comportamento de um aterro sobre solos argilosos moles reforçados com colunas de brita é analisado usando um modelo numérico baseado no método dos elementos finitos. Utiliza-se o conceito de cé - lu la unitária, que consiste no estudo isolado de uma coluna e do respectivo solo envolvente, com com por ta - men to axissimétrico. O modelo numérico i...

The problem of vertical stability in flexible anchored retaining walls is analyzed and the pattern of the behavior under conditions of poor vertical support is described, on the basis of results from case histories, small-scale tests, and numerical modeling. The possibility of shear stress mobilization in the soil-to-wall interface of anchored conc...

A estabilidade vertical de cortinas tipo Berlim ancoradas é substancialmente dependente da complexidade da interacção entre as diferentes partes da estrutura (cortina, ancoragens e maciço suportado). O aprofundamento da compreensão de certos aspectos dessa questão é conseguido re-examinando o problema do equilíbrio vertical à luz das metodologias d...

The highly variable nature of the deeply weathered Oporto granite posed significant challenges in the driving of the 2.3 km long C line and the 4 km long S line of the Oporto Metro project. Two 8.7 m diameter Herrenknecht EPB TBMs were used to excavate these tunnels and early problems were encountered due to over excavation and face collapse. Three...

Destaca-se o papel dos perfis metálicos verticais nas estruturas de contenção tipo Berlim definitivas e a importância do dimensionamento destas estruturas em relação ao carregamento vertical. Apresenta-se os resultados de um estudo paramétrico, usando um modelo de elementos finitos, de estruturas de contenção tipo Berlim definitivas considerando di...

Overall stability of geosynthetic-reinforced embankments on soft soils is analysed using two different methodologies: application of a numerical model based on the finite element method; use of a limit equilibrium method. These two methodologies are described and also applied on three geosynthetic-reinforced embankments on soft soils. One of the ca...

São por vezes executadas escavações urbanas com recurso a estruturas de contenção tipo Berlim em que os perfis metálicos verticais são instalados externamente à parede. O recurso a esta solução é normalmente justificado pela dificuldade de realização de furos tangentes ou muito próximos de empenas de edifícios vizinhos. Para além da sua maior expos...

Geotechnical behaviour of a reinforced embankment on soft ground is studied by a numerical model based on the finite element method. Special emphasis is given to the stress states (stress levels and pore pressures), displacements, tensile forces in the geosynthetic and overall stability, during and after construction. The influence of some paramete...

Limit state design applied to geotechnical structures requires the selection of characteristic values of ground parameters and the use of partial safety factors. These factors, and the way that characteristic values are selected, will govern the calculated probability of failure of the structure. The paper presents a methodology for estimating the...

Cited By (since 1996):3, Export Date: 1 October 2013, Source: Scopus

Numerical and field results of a reinforced embankment on soft ground constructed up to failure are compared. The first results were obtained by a model based on the finite element method and the second by pneumatic piezometers (pore pressures), horizontal profile tube and settlement cells (settlements), vertical inclinometers (horizontal displacem...

The Baixa-Chiado Station is part of Lisbon Metro network and consists of two enormous cavities with 240m2 cross section each. It is one of the largest underground engineering works ever built in clayey and sandy soils. For its execution the NATM was used. The settlements predicted in the design were high, even though the differentil settlements wer...

The Baixa-Chiado station is part of the Lisbon Metro and consists of 2 enormous cavities. For its execution NATM method was used. After the excavation of the first cavity, it was verified that differential settlements were much higher than values predicted. Thus increasing cracks appeared in the old buidings at surface. As a result compensation gro...

Foi realizada uma vasta campanha de investigação num local onde predominam os solos saprolíticos típicos da região do Porto. O estudo incluiu diversos tipos de ensaios in situ (SPT, CPT, DP, ensaios sísmicos Cross-Hole, SBPT, ensaios de placa) e de laboratório e, ainda, um ensaio de carga vertical de uma sapata de betão armado cuidadosamente instru...

In the north-western region of Portugal residual soils from granite are dominant. Their porous cemented structure leads to a complex geotechnical behaviour, quite distinct from that of transported soils with a similar grain size distribution. The paper describes some of the studies carried out at an experimental site on which a fairly homogeneous s...

O trabalho apresenta o estudo de uma escavação escorada num maciço de argila mole simulada numericamente com recurso a um modelo de cálculo elastoplástico baseado no método dos elementos finitos. Na análise dos resultados são postas em destaque as redistribuições de tensões por efeito de arco no maciço interessado pela escavação e identificados os...

An elastoplastic model is used to study the failure mechanisms of nailed walls during construction. These mechanisms may be determined by the soil-reinforcement bond resistance or by the failure of the nails. Theoretical analyses of the question currently ignore the ductility of the nails although it can play an important role in the behaviour of t...

The paper describes a rheological model based on a series of Kelvin models for analysing creep behaviour. This model is implemented in a finite element analysis to predict the behaviour of an instrumented sloped reinforced soil wall. The performance of the numerical model and the actual behaviour of the structure are compared. The analysis is carri...

This paper presents the results of the application of 2D and 3D finite element models to a railway tunnel excavated in granite residual soils in the north of Portugal. A brief description of the work and monitoring system is included and the results of the observation are compared with those calculated numerically. -Authors

The paper presents a study of bearing capacity failures of tied-back walls induced by vertical forces applied by the anchors. A review of some failures or incidents and small scale test results as well as an attempt of numerical simulation of a “case history” are included. Subsequently, a simple numerical case study is analysed in order to identify...

The characterization of the granitic mass of Porto for the design and construction of the Metro works of the city was based on weathering grades and structural features which were used for the derivation of the design parameters. The highly variable nature of the deeply weathered Oporto granite posed significant challenges in the driving of the 2.3...

The highly variable nature of the deeply weathered Oporto granite posed significant challenges in the driving of the 8.7km long Metro tunnels with 2 EPBTBMs. Early problems were encountered due to over excavation and face collapse in that extremely heterogeneous geology. Because of the last collapse with fatal consequences the project was interrupt...

In excavations supported by anchored concrete soldier-pile walls, the last stage of the excavation is determinant with regard to vertical stability. In a previous paper the authors applied limit analysis to study the vertical equilibrium of these walls and suggested the possible influence of the height of the last excavation level. In the present p...