Antonio Gens - Academia.edu (original) (raw)

Papers by Antonio Gens

Research paper thumbnail of A pressuremeter-based evaluation of structure in London Clay using a kinematic hardening constitutive model

Acta Geotechnica, Mar 5, 2020

Research paper thumbnail of Energy balance analyses during Standard Penetration Tests in a virtual calibration chamber

Computers and Geotechnics, May 1, 2021

Research paper thumbnail of Modelling a hydration and heating column test on unsaturated bentonite using a double-porosity approach

E3S web of conferences, 2023

Research paper thumbnail of A stable mesh-independent approach for numerical modelling of structured soils at large strains

Computers and Geotechnics, Dec 1, 2019

Research paper thumbnail of Grading evolution and critical state in a discrete numerical model of Fontainebleau sand

Research paper thumbnail of Mechanical behaviour of heavily compacted bentonite under high suction changes

Geotechnique, Feb 1, 2003

Research paper thumbnail of Irreversible Behaviour of Crushable Sands: a DEM Study

The irreversible behaviour of crushable sands is investigated by means of a Discrete Element Meth... more The irreversible behaviour of crushable sands is investigated by means of a Discrete Element Method (DEM) analogue. The calculations have been performed using a recently developed procedure to simulate particle crushing that significantly enhances the computational efficiency of the method. The DEM analogue is subjected to a comprehensive set of stress probes in the triaxial plane in order to identify the basic mechanisms contributing to the total deformation. Three contributions to incremental strains are distinguished: elastic, plastic-structural and plastic-crushing. The behaviour observed appears to be consistent with the classic tenets of elasto-plasticity. The plastic mechanisms associated with fabric changes and with crushing are, however, different. In addition, the plastic flows for the two mechanism do not follow the normality rule. The same type of behaviour has been obtained under a wide variety of stress conditions and stress levels.

Research paper thumbnail of Plasticity for crushable granular materials via DEM

Research paper thumbnail of DEM modelling of dynamic penetration in granular material

CRC Press eBooks, Jun 19, 2018

Research paper thumbnail of Homogenization of unsaturated bentonite during hydration

E3S Web of Conferences

Bentonite barriers are a key component in may designs of deep geological repositories for high le... more Bentonite barriers are a key component in may designs of deep geological repositories for high level nuclear waste. During the hydration stage, the bentonite undergoes non-uniform changes in dry density that may persist even after reaching a fully saturated state. Since dry density controls the properties of the bentonite that ensure the functions of safety of the barrier, the potential of bentonite for homogenization or otherwise is a matter of high relevance. The paper presents the results and the analyses of two hydration tests on initially heterogenous samples, especially designed to explore the phenomena and processes underlying the homogenisation of bentonite materials. The formulation and constitutive model used in the analyses are briefly presented followed by a description of the tests. Subsequently, the experimental dataobtained from the tests are discussed together with the results of the hydromechanical analyses performed. Particular attention is given to the degree of h...

Research paper thumbnail of FEBEX. Bentonite: origin, properties and fabrication of blocks

Research paper thumbnail of Geotechnical particle finite element method for modeling of soil-structure interaction under large deformation conditions

Journal of Rock Mechanics and Geotechnical Engineering, 2022

Research paper thumbnail of Homogenización de barreras de arcilla para residuos nucleares

Geotecnia, 2021

Las funciones de seguridad de las barreras de bentonita para residuos nucleares dependen principa... more Las funciones de seguridad de las barreras de bentonita para residuos nucleares dependen principalmente del valor de su densidad seca (o porosidad). La evolución de esta variable durante la fase transitoria de la barrera es compleja. El artículo presenta una formulación teórica para calcular, mediante análisis numéricos acoplados, los cambios de densidad seca debidos a la hidratación de la barrera, prestando una especial atención a los procesos de homogenización. Se ha adoptado un modelo constitutivo de doble estructura para representar de forma más realista el comportamiento mecánico (tensión-deformación) de la bentonita. Utilizando la formulación presentada, se han simulado satisfactoriamente dos ensayos de hidratación, con distintas condiciones de contorno, sobre muestras que exhibían un elevado grado de heterogeneidad inicial. Los análisis predicen correctamente la saturación final de la muestra, el valor de la presión final de hinchamiento y, sobre todo, el proceso de homogeniz...

Research paper thumbnail of DEM examination of SPT correction factors

EPJ Web of Conferences, 2021

The Standard Penetration Test (SPT) is the most widely used method for dynamic testing of soils. ... more The Standard Penetration Test (SPT) is the most widely used method for dynamic testing of soils. The test is simple and robust but difficult to control and not fully standardized. As a result, experimental results typically show large variations and poor repeatability. To mitigate that correction factors such as energy normalization and rod length have been introduced in SPT practice. This study provides an examination of the two correction factors using models based on the discrete element method (DEM).

Research paper thumbnail of DEM Investigation of Particle Crushing Effects on Static and Dynamic Penetration Tests

Springer Series in Geomechanics and Geoengineering, 2018

A 3-dimensional discrete element method model has been developed to simulate static and dynamic r... more A 3-dimensional discrete element method model has been developed to simulate static and dynamic rod penetration test in a calibration chamber. The chamber has been filled with a scaled analogue of Fontainebleau sand. Crushing effects on penetration results have been examined. It has been found that particle crushing reduces penetration resistance for both static and dynamic tests. Microscale observation of crushed particles has been conducted. It is shown that dynamic impact causes more crushing events. The crushed particles are distributed within 2–3 radius from the rod for both tests.

Research paper thumbnail of Discrete Simulation of Cone Penetration in Granular Materials

The simulation of penetration problems into granular materials is a challenging problem as it inv... more The simulation of penetration problems into granular materials is a challenging problem as it involves large deformations and displacements as well as strong non-linearities affecting material behaviour, geometry and contact surfaces. In this contribution, the Discrete Element Method (DEM) has been adopted as the modelling formulation. Attention is focused on the simulation of cone penetration, a basic reconnaissance tool in geotechnical engineering, although the approach can be readily extended to other penetration problems. It is shown that DEM analysis results in a very close quantitative representation of the cone resistance obtained in calibration chambers under a wide range of conditions. DEM analyses also provides, using appropriate averaging techniques, relevant information concerning mesoscale continuum variables (stresses and strains) that appear to be in agreement with physical calibration chamber observations. The examination of microstructural variables contributes to a...

Research paper thumbnail of Marchetti Flat Dilatometer Tests in a Virtual Calibration Chamber

Geotechnical Testing Journal, 2018

Research paper thumbnail of High resolution incremental stress testing of crushable granular materials

E3S Web of Conferences, 2019

The incremental behaviour of crushable sands is investigated by means of a Discrete Element Metho... more The incremental behaviour of crushable sands is investigated by means of a Discrete Element Method (DEM) based analogue. The DEM sample is subjected to a comprehensive set of small stress perturbations in the triaxial plane in order to identify the basic mechanisms contributing to the corresponding strain response. Three contributions to incremental strains are distinguished: elastic, plastic-structural and plastic-crushing. The behaviour observed appears to be consistent with the classic tenets of elasto-plasticity. It is also shown that high resolution probing is required to identify significant features such as elastic anisotropy and irreversible effects on the tangent bulk and shear moduli. As a consequence, computational efficiency is therefore a must for numerical studies of incremental response.

Research paper thumbnail of Micromechanical inspection of incremental behaviour of crushable soils

Research paper thumbnail of Standard penetration testing in a virtual calibration chamber

Computers and Geotechnics, 2019

Research paper thumbnail of A pressuremeter-based evaluation of structure in London Clay using a kinematic hardening constitutive model

Acta Geotechnica, Mar 5, 2020

Research paper thumbnail of Energy balance analyses during Standard Penetration Tests in a virtual calibration chamber

Computers and Geotechnics, May 1, 2021

Research paper thumbnail of Modelling a hydration and heating column test on unsaturated bentonite using a double-porosity approach

E3S web of conferences, 2023

Research paper thumbnail of A stable mesh-independent approach for numerical modelling of structured soils at large strains

Computers and Geotechnics, Dec 1, 2019

Research paper thumbnail of Grading evolution and critical state in a discrete numerical model of Fontainebleau sand

Research paper thumbnail of Mechanical behaviour of heavily compacted bentonite under high suction changes

Geotechnique, Feb 1, 2003

Research paper thumbnail of Irreversible Behaviour of Crushable Sands: a DEM Study

The irreversible behaviour of crushable sands is investigated by means of a Discrete Element Meth... more The irreversible behaviour of crushable sands is investigated by means of a Discrete Element Method (DEM) analogue. The calculations have been performed using a recently developed procedure to simulate particle crushing that significantly enhances the computational efficiency of the method. The DEM analogue is subjected to a comprehensive set of stress probes in the triaxial plane in order to identify the basic mechanisms contributing to the total deformation. Three contributions to incremental strains are distinguished: elastic, plastic-structural and plastic-crushing. The behaviour observed appears to be consistent with the classic tenets of elasto-plasticity. The plastic mechanisms associated with fabric changes and with crushing are, however, different. In addition, the plastic flows for the two mechanism do not follow the normality rule. The same type of behaviour has been obtained under a wide variety of stress conditions and stress levels.

Research paper thumbnail of Plasticity for crushable granular materials via DEM

Research paper thumbnail of DEM modelling of dynamic penetration in granular material

CRC Press eBooks, Jun 19, 2018

Research paper thumbnail of Homogenization of unsaturated bentonite during hydration

E3S Web of Conferences

Bentonite barriers are a key component in may designs of deep geological repositories for high le... more Bentonite barriers are a key component in may designs of deep geological repositories for high level nuclear waste. During the hydration stage, the bentonite undergoes non-uniform changes in dry density that may persist even after reaching a fully saturated state. Since dry density controls the properties of the bentonite that ensure the functions of safety of the barrier, the potential of bentonite for homogenization or otherwise is a matter of high relevance. The paper presents the results and the analyses of two hydration tests on initially heterogenous samples, especially designed to explore the phenomena and processes underlying the homogenisation of bentonite materials. The formulation and constitutive model used in the analyses are briefly presented followed by a description of the tests. Subsequently, the experimental dataobtained from the tests are discussed together with the results of the hydromechanical analyses performed. Particular attention is given to the degree of h...

Research paper thumbnail of FEBEX. Bentonite: origin, properties and fabrication of blocks

Research paper thumbnail of Geotechnical particle finite element method for modeling of soil-structure interaction under large deformation conditions

Journal of Rock Mechanics and Geotechnical Engineering, 2022

Research paper thumbnail of Homogenización de barreras de arcilla para residuos nucleares

Geotecnia, 2021

Las funciones de seguridad de las barreras de bentonita para residuos nucleares dependen principa... more Las funciones de seguridad de las barreras de bentonita para residuos nucleares dependen principalmente del valor de su densidad seca (o porosidad). La evolución de esta variable durante la fase transitoria de la barrera es compleja. El artículo presenta una formulación teórica para calcular, mediante análisis numéricos acoplados, los cambios de densidad seca debidos a la hidratación de la barrera, prestando una especial atención a los procesos de homogenización. Se ha adoptado un modelo constitutivo de doble estructura para representar de forma más realista el comportamiento mecánico (tensión-deformación) de la bentonita. Utilizando la formulación presentada, se han simulado satisfactoriamente dos ensayos de hidratación, con distintas condiciones de contorno, sobre muestras que exhibían un elevado grado de heterogeneidad inicial. Los análisis predicen correctamente la saturación final de la muestra, el valor de la presión final de hinchamiento y, sobre todo, el proceso de homogeniz...

Research paper thumbnail of DEM examination of SPT correction factors

EPJ Web of Conferences, 2021

The Standard Penetration Test (SPT) is the most widely used method for dynamic testing of soils. ... more The Standard Penetration Test (SPT) is the most widely used method for dynamic testing of soils. The test is simple and robust but difficult to control and not fully standardized. As a result, experimental results typically show large variations and poor repeatability. To mitigate that correction factors such as energy normalization and rod length have been introduced in SPT practice. This study provides an examination of the two correction factors using models based on the discrete element method (DEM).

Research paper thumbnail of DEM Investigation of Particle Crushing Effects on Static and Dynamic Penetration Tests

Springer Series in Geomechanics and Geoengineering, 2018

A 3-dimensional discrete element method model has been developed to simulate static and dynamic r... more A 3-dimensional discrete element method model has been developed to simulate static and dynamic rod penetration test in a calibration chamber. The chamber has been filled with a scaled analogue of Fontainebleau sand. Crushing effects on penetration results have been examined. It has been found that particle crushing reduces penetration resistance for both static and dynamic tests. Microscale observation of crushed particles has been conducted. It is shown that dynamic impact causes more crushing events. The crushed particles are distributed within 2–3 radius from the rod for both tests.

Research paper thumbnail of Discrete Simulation of Cone Penetration in Granular Materials

The simulation of penetration problems into granular materials is a challenging problem as it inv... more The simulation of penetration problems into granular materials is a challenging problem as it involves large deformations and displacements as well as strong non-linearities affecting material behaviour, geometry and contact surfaces. In this contribution, the Discrete Element Method (DEM) has been adopted as the modelling formulation. Attention is focused on the simulation of cone penetration, a basic reconnaissance tool in geotechnical engineering, although the approach can be readily extended to other penetration problems. It is shown that DEM analysis results in a very close quantitative representation of the cone resistance obtained in calibration chambers under a wide range of conditions. DEM analyses also provides, using appropriate averaging techniques, relevant information concerning mesoscale continuum variables (stresses and strains) that appear to be in agreement with physical calibration chamber observations. The examination of microstructural variables contributes to a...

Research paper thumbnail of Marchetti Flat Dilatometer Tests in a Virtual Calibration Chamber

Geotechnical Testing Journal, 2018

Research paper thumbnail of High resolution incremental stress testing of crushable granular materials

E3S Web of Conferences, 2019

The incremental behaviour of crushable sands is investigated by means of a Discrete Element Metho... more The incremental behaviour of crushable sands is investigated by means of a Discrete Element Method (DEM) based analogue. The DEM sample is subjected to a comprehensive set of small stress perturbations in the triaxial plane in order to identify the basic mechanisms contributing to the corresponding strain response. Three contributions to incremental strains are distinguished: elastic, plastic-structural and plastic-crushing. The behaviour observed appears to be consistent with the classic tenets of elasto-plasticity. It is also shown that high resolution probing is required to identify significant features such as elastic anisotropy and irreversible effects on the tangent bulk and shear moduli. As a consequence, computational efficiency is therefore a must for numerical studies of incremental response.

Research paper thumbnail of Micromechanical inspection of incremental behaviour of crushable soils

Research paper thumbnail of Standard penetration testing in a virtual calibration chamber

Computers and Geotechnics, 2019