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Paulo B. Lourenço - One of the best experts on this subject based on the ideXlab platform.

  • A DEM based tool for the safety analysis of Masonry gravity Dams
    Engineering Structures, 2014
    Co-Authors: E. M. Bretas, José V. Lemos, Paulo B. Lourenço
    Abstract:

    Abstract 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 discontinuum analysis. A contact formulation was developed, which represents the interaction between macroblocks in terms of contacts established between elementary blocks, based on an accurate edge–edge approach. The main numerical aspects of the model are described, addressing in particular the contact creation and update procedures, and the numerical devices that support an efficient explicit solution algorithm. An application to the safety evaluation of an existing Masonry Dam is discussed, including stress analysis in the structure, and the assessment of sliding failure mechanisms, involving different paths in the vicinity of the Dam–rock interface.

  • Hydromechanical Analysis of Masonry Gravity Dams and their Foundations
    Rock Mechanics and Rock Engineering, 2013
    Co-Authors: E. M. Bretas, José V. Lemos, Paulo B. Lourenço
    Abstract:

    A numerical model for the hydromechanical analysis of Masonry Dams based on the discrete element method is presented. The Dam and the rock foundation are represented as block assemblies, and a coupled flow-stress analysis is performed in an integrated manner for the entire system. Complex block shapes may be obtained by assembling elementary blocks into macroblocks, allowing the application of the model to situations ranging from equivalent continuum to fully discontinuum analysis. A contact formulation was developed based on an accurate edge–edge approach, incorporating mechanical and hydraulic behavior. The main numerical aspects are described, with an emphasis in the flow analysis explicit algorithm. An application to an existing Masonry Dam is presented, analyzing its present condition, with excessive seepage, and the proposed rehabilitation intervention. An evaluation of sliding failure mechanisms was also performed, showing the expected improvement in the safety of the structure.

E. M. Bretas - One of the best experts on this subject based on the ideXlab platform.

  • Masonry DamS – ANALYSIS OF THE HISTORICAL PROFILES
    2016
    Co-Authors: E. M. Bretas, J. V. Lemos, P. B. Lourenço
    Abstract:

    The significant advances in Masonry Dam design that took place in the second half of the 19th century are analyzed and discussed within the context of the historical development of Dam construction. Particular reference is made to the gravity Dam profiles proposed by Sazilly, Delocre and Rankine, who pioneered the application of engineering concepts to Dam design, basing the Dam profile on the allowable stresses for the conditions of empty and full reservoir. These historical profiles are analyzed taking into consideration the present safety assessment procedures, by means of a numerical application developed for this purpose, based on limit analysis equilibrium methods, which considers the sliding failure mechanisms, the most critical for these structures. The study underlines the key role of uplift pressures, which was only addressed by Lévy after the accident of Bouzey Dam, and provides a critica

  • A DEM based tool for the safety analysis of Masonry gravity Dams
    Engineering Structures, 2014
    Co-Authors: E. M. Bretas, José V. Lemos, Paulo B. Lourenço
    Abstract:

    Abstract 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 discontinuum analysis. A contact formulation was developed, which represents the interaction between macroblocks in terms of contacts established between elementary blocks, based on an accurate edge–edge approach. The main numerical aspects of the model are described, addressing in particular the contact creation and update procedures, and the numerical devices that support an efficient explicit solution algorithm. An application to the safety evaluation of an existing Masonry Dam is discussed, including stress analysis in the structure, and the assessment of sliding failure mechanisms, involving different paths in the vicinity of the Dam–rock interface.

  • Hydromechanical Analysis of Masonry Gravity Dams and their Foundations
    Rock Mechanics and Rock Engineering, 2013
    Co-Authors: E. M. Bretas, José V. Lemos, Paulo B. Lourenço
    Abstract:

    A numerical model for the hydromechanical analysis of Masonry Dams based on the discrete element method is presented. The Dam and the rock foundation are represented as block assemblies, and a coupled flow-stress analysis is performed in an integrated manner for the entire system. Complex block shapes may be obtained by assembling elementary blocks into macroblocks, allowing the application of the model to situations ranging from equivalent continuum to fully discontinuum analysis. A contact formulation was developed based on an accurate edge–edge approach, incorporating mechanical and hydraulic behavior. The main numerical aspects are described, with an emphasis in the flow analysis explicit algorithm. An application to an existing Masonry Dam is presented, analyzing its present condition, with excessive seepage, and the proposed rehabilitation intervention. An evaluation of sliding failure mechanisms was also performed, showing the expected improvement in the safety of the structure.

Lourenço, Paulo B. - One of the best experts on this subject based on the ideXlab platform.

  • Numerical modelling of Masonry gravity Dams considering the internal structure of the material
    2014
    Co-Authors: Bretas E. M., Lemos J., Lourenço, Paulo B.
    Abstract:

    Frequently, numerical models of Masonry Dams disregard the discontinuous nature of the material. In some cases, those discontinuities control the structural and hydraulic behaviour of the Masonry Dam. The Masonry proprieties are influenced by the quality of the material and the laying scheme of the stones on the external faces as well as in the inner material. The Discrete Element Method (DEM) has been used on analyses of gravity Masonry Dams. The capacity to model the discontinuities explicitly and the ability to perform coupled analyses are two significant benefits of the DEM. The DEM application used in this paper is presented, stressing the description of the calculation cycle. Seven examples of numerical analyses of gravity Masonry Dams are presented. Three of them consider the discontinuous nature of the Dam body, in order to study the loss of cohesion scenario, the crack propagation scenario and the seismic performance of a Masonry Dam. The remainder four examples are aimed at stress analysis, global stability, hydromechanical analysis and the permanent sliding resulting from a seismic event

  • A DEM based tool for the safety analysis of Masonry gravity Dams
    'Elsevier BV', 2014
    Co-Authors: Bretas E. M., Lemos José, Lourenço, Paulo B.
    Abstract:

    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 discontinuum analysis. A contact formulation was developed, which represents the interaction between macroblocks in terms of contacts established between elementary blocks, based on an accurate edge-edge approach. The main numerical aspects of the model are described, addressing in particular the contact creation and update procedures, and the numerical devices that support an efficient explicit solution algorithm. An application to the safety evaluation of an existing Masonry Dam is discussed, including stress analysis in the structure, and the assessment of sliding failure mechanisms, involving different paths in the vicinity of the Dam-rock interface.Permission by EDP to present the example data is gratefully acknowledged. The first author also acknowledges the financial support of the Portuguese Science Foundation (Fundacao de Ciencia e Tecnologia, FCT), through Grant SFRH/BD/43585/2008

  • Hydromechanical analysis of Masonry gravity Dams and their foundations
    'Springer Science and Business Media LLC', 2013
    Co-Authors: Bretas E. M., Lemos José, Lourenço, Paulo B.
    Abstract:

    A numerical model for the hydromechanical analysis of Masonry Dams based on the discrete element method is presented. The Dam and the rock foundation are represented as block assemblies, and a coupled flow-stress analysis is performed in an integrated manner for the entire system. Complex block shapes may be obtained by assembling elementary blocks into macroblocks, allowing the application of the model to situations ranging from equivalent continuum to fully discontinuum analysis. A contact formulation was developed based on an accurate edge-edge approach, incorporating mechanical and hydraulic behavior. The main numerical aspects are described, with an emphasis in the flow analysis explicit algorithm. An application to an existing Masonry Dam is presented, analyzing its present condition, with excessive seepage, and the proposed rehabilitation intervention. An evaluation of sliding failure mechanisms was also performed, showing the expected improvement in the safety of the structure.Permission by EDP to present the example data is gratefully acknowledged. The first author also acknowledges the financial support of the Portuguese Science Foundation (Fundacao de Ciencia e Tecnologia, FCT), through grant SFRH/BD/43585/2008

  • Masonry Dams : analysis of the historical profiles of Sazilly, Delocre and Rankine
    'Informa UK Limited', 2012
    Co-Authors: Bretas E. M., Lemos José, Lourenço, Paulo B.
    Abstract:

    The significant advances in Masonry Dam design that took place in the second half of the 19th century are analyzed and discussed within the context of the historical development of Dam construction. Particular reference is made to the gravity Dam profiles proposed by Sazilly, Delocre and Rankine, who pioneered the application of engineering concepts to Dam design, basing the Dam profile on the allowable stresses for the conditions of empty and full reservoir. These historical profiles are analyzed taking into consideration the present safety assessment procedures, by means of a numerical application developed for this purpose, based on limit analysis equilibrium methods, which considers the sliding failure mechanisms, the most critical for these structures. The study underlines the key role of uplift pressures, which was only addressed by Lévy after the accident of Bouzey Dam, and provides a critical understanding of the original design concepts, which is essential for the rehabilitation of these historical structures.This work has been funded by FCT (Portuguese Foundation for Science and Technology) through the PhD grant SFRH/BD/43585/2008, for which the first author is grateful

José V. Lemos - One of the best experts on this subject based on the ideXlab platform.

  • A DEM based tool for the safety analysis of Masonry gravity Dams
    Engineering Structures, 2014
    Co-Authors: E. M. Bretas, José V. Lemos, Paulo B. Lourenço
    Abstract:

    Abstract 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 discontinuum analysis. A contact formulation was developed, which represents the interaction between macroblocks in terms of contacts established between elementary blocks, based on an accurate edge–edge approach. The main numerical aspects of the model are described, addressing in particular the contact creation and update procedures, and the numerical devices that support an efficient explicit solution algorithm. An application to the safety evaluation of an existing Masonry Dam is discussed, including stress analysis in the structure, and the assessment of sliding failure mechanisms, involving different paths in the vicinity of the Dam–rock interface.

  • Hydromechanical Analysis of Masonry Gravity Dams and their Foundations
    Rock Mechanics and Rock Engineering, 2013
    Co-Authors: E. M. Bretas, José V. Lemos, Paulo B. Lourenço
    Abstract:

    A numerical model for the hydromechanical analysis of Masonry Dams based on the discrete element method is presented. The Dam and the rock foundation are represented as block assemblies, and a coupled flow-stress analysis is performed in an integrated manner for the entire system. Complex block shapes may be obtained by assembling elementary blocks into macroblocks, allowing the application of the model to situations ranging from equivalent continuum to fully discontinuum analysis. A contact formulation was developed based on an accurate edge–edge approach, incorporating mechanical and hydraulic behavior. The main numerical aspects are described, with an emphasis in the flow analysis explicit algorithm. An application to an existing Masonry Dam is presented, analyzing its present condition, with excessive seepage, and the proposed rehabilitation intervention. An evaluation of sliding failure mechanisms was also performed, showing the expected improvement in the safety of the structure.

Bretas E. M. - One of the best experts on this subject based on the ideXlab platform.

  • Numerical modelling of Masonry gravity Dams considering the internal structure of the material
    2014
    Co-Authors: Bretas E. M., Lemos J., Lourenço, Paulo B.
    Abstract:

    Frequently, numerical models of Masonry Dams disregard the discontinuous nature of the material. In some cases, those discontinuities control the structural and hydraulic behaviour of the Masonry Dam. The Masonry proprieties are influenced by the quality of the material and the laying scheme of the stones on the external faces as well as in the inner material. The Discrete Element Method (DEM) has been used on analyses of gravity Masonry Dams. The capacity to model the discontinuities explicitly and the ability to perform coupled analyses are two significant benefits of the DEM. The DEM application used in this paper is presented, stressing the description of the calculation cycle. Seven examples of numerical analyses of gravity Masonry Dams are presented. Three of them consider the discontinuous nature of the Dam body, in order to study the loss of cohesion scenario, the crack propagation scenario and the seismic performance of a Masonry Dam. The remainder four examples are aimed at stress analysis, global stability, hydromechanical analysis and the permanent sliding resulting from a seismic event

  • A DEM based tool for the safety analysis of Masonry gravity Dams
    'Elsevier BV', 2014
    Co-Authors: Bretas E. M., Lemos José, Lourenço, Paulo B.
    Abstract:

    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 discontinuum analysis. A contact formulation was developed, which represents the interaction between macroblocks in terms of contacts established between elementary blocks, based on an accurate edge-edge approach. The main numerical aspects of the model are described, addressing in particular the contact creation and update procedures, and the numerical devices that support an efficient explicit solution algorithm. An application to the safety evaluation of an existing Masonry Dam is discussed, including stress analysis in the structure, and the assessment of sliding failure mechanisms, involving different paths in the vicinity of the Dam-rock interface.Permission by EDP to present the example data is gratefully acknowledged. The first author also acknowledges the financial support of the Portuguese Science Foundation (Fundacao de Ciencia e Tecnologia, FCT), through Grant SFRH/BD/43585/2008

  • Hydromechanical analysis of Masonry gravity Dams and their foundations
    'Springer Science and Business Media LLC', 2013
    Co-Authors: Bretas E. M., Lemos José, Lourenço, Paulo B.
    Abstract:

    A numerical model for the hydromechanical analysis of Masonry Dams based on the discrete element method is presented. The Dam and the rock foundation are represented as block assemblies, and a coupled flow-stress analysis is performed in an integrated manner for the entire system. Complex block shapes may be obtained by assembling elementary blocks into macroblocks, allowing the application of the model to situations ranging from equivalent continuum to fully discontinuum analysis. A contact formulation was developed based on an accurate edge-edge approach, incorporating mechanical and hydraulic behavior. The main numerical aspects are described, with an emphasis in the flow analysis explicit algorithm. An application to an existing Masonry Dam is presented, analyzing its present condition, with excessive seepage, and the proposed rehabilitation intervention. An evaluation of sliding failure mechanisms was also performed, showing the expected improvement in the safety of the structure.Permission by EDP to present the example data is gratefully acknowledged. The first author also acknowledges the financial support of the Portuguese Science Foundation (Fundacao de Ciencia e Tecnologia, FCT), through grant SFRH/BD/43585/2008

  • Masonry Dams : analysis of the historical profiles of Sazilly, Delocre and Rankine
    'Informa UK Limited', 2012
    Co-Authors: Bretas E. M., Lemos José, Lourenço, Paulo B.
    Abstract:

    The significant advances in Masonry Dam design that took place in the second half of the 19th century are analyzed and discussed within the context of the historical development of Dam construction. Particular reference is made to the gravity Dam profiles proposed by Sazilly, Delocre and Rankine, who pioneered the application of engineering concepts to Dam design, basing the Dam profile on the allowable stresses for the conditions of empty and full reservoir. These historical profiles are analyzed taking into consideration the present safety assessment procedures, by means of a numerical application developed for this purpose, based on limit analysis equilibrium methods, which considers the sliding failure mechanisms, the most critical for these structures. The study underlines the key role of uplift pressures, which was only addressed by Lévy after the accident of Bouzey Dam, and provides a critical understanding of the original design concepts, which is essential for the rehabilitation of these historical structures.This work has been funded by FCT (Portuguese Foundation for Science and Technology) through the PhD grant SFRH/BD/43585/2008, for which the first author is grateful