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  • Geohazards: Risk Assessment, Mitigation and Prevention

     Arroyo Alvarez de Toledo, Marcos
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  • CIMAVA

     Arroyo Alvarez de Toledo, Marcos
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  • Rendimiento, desgaste y abrasividad en excavación mecanizada de túneles en terrenos heterogéneos.  Open access

     Gonzalez Paez, Claudia
    Department of Geotechnical Engineering and Geo-Sciences, Universitat Politècnica de Catalunya
    Theses

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    Una base de datos de 33 km de registros de túnel de EPB en la zona de Barcelona se ha examinado en detalle desde el punto de vista de recambio de herramientas de corte y rendimiento de la excavación mecanizada. La base de datos incluye túneles en suelos blandos, en rocas medias y duras y en condiciones mixtas de roca y suelo. Los datos recabados incluyen registros de cambios de herramientas, operaciones de la maquina (avance, empuje, par, etc.) y propiedades geotécnicas, con un énfasis sistemático en mediciones de abrasividad de los diferentes materiales perforados. Para obtener una descripción homogénea de la abrasividad se realizaron mediciones de abrasividad del tipo LCPC en todos los materiales. Un resumen descriptivo de las principales tendencias reveladas por los datos se presenta en esta tesis.Las paradas de las máquinas durante la perforación se pueden clasificar entre aquellas debidas a un mantenimiento planificado y aquellas debidas a incidentes imprevistos. Los últimos pueden resultar ser decisivos cuando evaluamos el éxito de una perforación, aunque normalmente no son considerados en el proyecto. Uno de los aspectos más exigentes del mantenimiento desde el punto de vista operativo es el de las herramientas de corte, ya que su revisión y posible sustitución siempre implica paradas de la máquina, y como que a menudo es necesario tener acceso al frente, es con frecuencia una operación lenta y difícil. Por lo tanto, es deseable programar el mantenimiento de la cabeza de corte con la precisión máxima posible. Para llevar a cabo tal programación dos aspectos son necesarios: la identificación de ¿umbrales de desgaste¿ de las herramientas y un método que permita estimar el desgaste para cada herramienta como consecuencia de la operación. El objetivo de este estudio es investigar cómo enfrentarse a este problema cuando el medio es heterogéneo y la excavación es mecanizada mediante EPB.Se tiene en cuenta sistemáticamente la heterogeneidad geotécnica transversal y longitudinal. La heterogeneidad longitudinal se usa para segmentar la base de datos en unidades homogéneas. La heterogeneidad transversal (dentro de la sección) se estima por un conjunto de factores de impacto en la presente desarrollados FI.El concepto de energía específica (SE) fue aplicado para evaluar la eficiencia total de la excavación. Procedimientos anteriores para computar SE en excavaciones con TBM fueron adaptados a excavaciones con maquina EPB en modo cerrado. Se tienen en cuenta explícitamente el soporte del frente y el momento rotacional debido a la presión de la tierra. Varios métodos existentes para predecir la tasa de penetración y la vida útil de las herramientas se evalúan respecto a los resultados de la base de datos. Siempre que fuera necesario se realizaron recalibraciones de estos procedimientos.Basadas en un análisis sistemático de los resultados de la base de datos, se proponen nuevas relaciones de origen empírico para estimar la tasa de penetración a partir de otros parámetros operacionales y las propiedades del suelo promediadas por sección. La exactitud de algunas aproximaciones implicadas (concretamente el uso de un tiempo de vida útil equivalente) se ha encontrado razonable usando los resultados de una excavación con los datos que eran lo más exactos posibles. Las relaciones propuestas serian mayormente aplicables como puntos de partida en proyectos en los cuales la geología está compuesta de suelos y rocas blandas y donde son predominantes los frentes heterogéneos.

    Una base de datos de 33 km de registros de túnel de EPB en la zona de Barcelona se ha examinado en detalle desde el punto de vista de recambio de herramientas de corte y rendimiento de la excavación mecanizada. La base de datos incluye túneles en suelos blandos, en rocas medias y duras y en condiciones mixtas de roca y suelo. Los datos recabados incluyen registros de cambios de herramientas, operaciones de la maquina (avance, empuje, par, etc.) y propiedades geotécnicas, con un énfasis sistemático en mediciones de abrasividad de los diferentes materiales perforados. Para obtener una descripción homogénea de la abrasividad se realizaron mediciones de abrasividad del tipo LCPC en todos los materiales. Un resumen descriptivo de las principales tendencias reveladas por los datos se presenta en esta tesis. Las paradas de las máquinas durante la perforación se pueden clasificar entre aquellas debidas a un mantenimiento planificado y aquellas debidas a incidentes imprevistos. Los últimos pueden resultar ser decisivos cuando evaluamos el éxito de una perforación, aunque normalmente no son considerados en el proyecto. Uno de los aspectos más exigentes del mantenimiento desde el punto de vista operativo es el de las herramientas de corte, ya que su revisión y posible sustitución siempre implica paradas de la máquina, y como que a menudo es necesario tener acceso al frente, es con frecuencia una operación lenta y difícil. Por lo tanto, es deseable programar el mantenimiento de la cabeza de corte con la precisión máxima posible. Para llevar a cabo tal programación dos aspectos son necesarios: la identificación de ¿umbrales de desgaste¿ de las herramientas y un método que permita estimar el desgaste para cada herramienta como consecuencia de la operación. El objetivo de este estudio es investigar cómo enfrentarse a este problema cuando el medio es heterogéneo y la excavación es mecanizada mediante EPB. Se tiene en cuenta sistemáticamente la heterogeneidad geotécnica transversal y longitudinal. La heterogeneidad longitudinal se usa para segmentar la base de datos en unidades homogéneas. La heterogeneidad transversal (dentro de la sección) se estima por un conjunto de factores de impacto en la presente desarrollados FI. El concepto de energía específica (SE) fue aplicado para evaluar la eficiencia total de la excavación. Procedimientos anteriores para computar SE en excavaciones con TBM fueron adaptados a excavaciones con maquina EPB en modo cerrado. Se tienen en cuenta explícitamente el soporte del frente y el momento rotacional debido a la presión de la tierra. Varios métodos existentes para predecir la tasa de penetración y la vida útil de las herramientas se evalúan respecto a los resultados de la base de datos. Siempre que fuera necesario se realizaron recalibraciones de estos procedimientos. Basadas en un análisis sistemático de los resultados de la base de datos, se proponen nuevas relaciones de origen empírico para estimar la tasa de penetración a partir de otros parámetros operacionales y las propiedades del suelo promediadas por sección. La exactitud de algunas aproximaciones implicadas (concretamente el uso de un tiempo de vida útil equivalente) se ha encontrado razonable usando los resultados de una excavación con los datos que eran lo más exactos posibles. Las relaciones propuestas serian mayormente aplicables como puntos de partida en proyectos en los cuales la geología está compuesta de suelos y rocas blandas y donde son predominantes los frentes heterogéneos.

    A database of 33 km of EPB tunnel records in the Barcelona area has been examined in detail from the point of view of cutting tool replacement and performance of the mechanized excavation. The database includes tunnels in soft soils, in hard and medium rocks and in mixed soil-rock conditions. Data gathered includes tool changing records, machine operation (advance, thrust, torque, etc.) and geotechnical properties, with a systematic emphasis on abrasivity measurements of the different materials perforated. To obtain a homogeneous description of abrasivity LCPC-type abrasive measurements were made in all the materials. A descriptive summary of the main trends revealed by the data is presented in this thesis. Machine downtimes during perforation can be classified into those due to planned maintenance and those due to unforeseen incidents. The latter can turn out to be decisive when assessing the success of a perforation, even though they are not usually considered in the project. One of the most demanding aspects of maintenance from an operational point of view is that of the cutting tools, since their revision and possible substitution always involves machine stops and, since it is often necessary to have access to the face, this is frequently a slow and difficult operation. Thus, it is desirable to schedule the cutter head maintenance operations with the highest possible precision. To carry out such scheduling two aspects are necessary: the identification of ¿wear thresholds¿ of the tools and a method that allows estimating the wear for each tool as a result of the operation. The objective of this study is to investigate how to tackle this problem when the media is heterogeneous and the excavation is mechanized by EPB. Transversal and longitudinal geotechnical heterogeneity is systematically accounted for. Longitudinal heterogeneity is used to segment the database in homogeneous units. Transversal (within section) heterogeneity is gauged by a set of newly developed impact factors FI. The specific energy concept (SE) was applied to evaluate overall excavation efficiency. Previous procedures to compute SE in TBM drives were adapted to excavations by EPB machine in closed mode. Face support and rotational moment due to earth pressure at the front face are taken explicitly into account. Several existing methods to predict penetration rate and tool service life are evaluated against the database results. Recalibrations of these procedures were performed when required. Based on a systematic analysis of the database results, new empirically based relations are proposed to estimate penetration rate from other operation parameters and section-averaged ground properties. The accuracy of some approximations involved (namely the use of an equivalent tool life time) has been found reasonable using the results of one drive were more exact computations were possible. The proposed relations would be mostly applicable as starting points in projects in which the geology is composed mostly of soils and soft rock and where the heterogeneous faces are predominant.

  • Cone Penetration Test in a Virtual Calibration Chamber  Open access

     Butlanska, Joanna
    Department of Geotechnical Engineering and Geo-Sciences, Universitat Politècnica de Catalunya
    Theses

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    Los ensayos de penetración estática de cono (CPT) son una de las herramientas más importantes en el reconocimiento geotécnico. La interpretación de los resultados de ensayo en arcilla ha avanzado considerablemente desde un punto de vista teórico y numérico. Sin embargo la interpretación de los resultados en los materiales granulares por ejemplo arena) todavía está basada en correlaciones empíricas provenientes de las pruebas realizadas en cámaras de calibración (CC), donde el estado del suelo y sus propiedades pueden ser controlados. Las cámaras de calibración son equipos relativamente grandes, y los ensayos en ellas son bastante costosos en tiempo y recursos. Por otra parte, las pruebas se realizan en muestras de arenas reconstituidas cuyas propiedades varían respecto de los depósitos naturales de donde provienen. Por lo tanto, las correlaciones desarrolladas en un tipo de arena podrían no ser adecuadas para otro depósito distinto. Cámaras de calibración numéricas (virtuales) basadas en el método de elementos discretos (DEM) podrían ofrecer una alternativa interesante a los ensayos físicos. Este estudio es el primer intento de realizar una simulación basadas en el método de los elementos discretos tridimensionales de ensayos de penetración de cono. El código comercial tridimensional (PFC3D) ha sido usado para desarrollar el modelo de CPT de Cámara de Calibración Virtual (CPT VCC). Para alcanzar este objetivo fueron necesarios varios pasos. En primer lugar, se llevó acabo la calibración de un material discreto análogo a arena de Ticino mediante ensayos elementales. A continuación se construyó el modelo CPT VCC. Un análisis dimensional exhaustivo mostró que la mejor opción para crear un modelo eficiente y real era llenar la cámara con un material con el tamaño de grano 50 veces mayor que el de la arena de Ticino. Se propuso una técnica original de filtrado para extraer la resistencia de punta estacionaria. Se realizó una serie básica de simulaciones para explorar el efecto de la tensión inicial y la densidad relativa sobre la resistencia de cono. Los resultados obtenidos de las simulaciones se ajustan estrechamente a las tendencias establecidas previamente en cámaras físicas. Este resultado fue tomado como una validación general del programa de simulación propuesto. Desde el punto de vista de la micro-mecánica, el material granular es muy discontinuo y no homogéneo. La obtención de un estado inicial homogéneo (especialmente en la zona de penetración del cono) es crucial para obtener resultados fácilmente interpretables. Por lo tanto se han desarrollado procedimientos específicos para evaluar heterogeneidades del estado inicial. Los resultados manifestaron el papel clave del contorno de modelo (paredes rígidas), tanto pasivo como activo (servo-controlados), durante la formación del modelo. Los modelos basados en el DEM puede proporcionar resultados a varios niveles de la resolución, es decir del micro-, meso- y macro escala. Se ha realizado una gran serie de VCC CPT. Las simulaciones se realizaron para modelos con diferentes posiciones en las paredes horizontales de servo-control, varios tamaños de cámara, varios tamaños del cono y de las partículas y dos condiciones de contorno. Los resultados se analizaron centrándose en varios aspectos como el tamaño de la cámara, el tamaño de las partículas y los efectos de condiciones de contorno sobre el valor de la resistencia de punta. Un número limitado de los CPT fue examinado desde el punto de vista de la resistencia del fuste del cono. Se observó que la mayoría de las tendencias y los resultados obtenidos estaban de acuerdo con resultados previos obtenidos en ensayos físicos. El trabajo presentado en esta tesis debería facilitar futuras calibraciones CPT en materiales granulados.

    Cone penetration test (CPT) is a fast and reliable site investigation tool for exploring soils and soft ground. While the interpretation of the test results in clay has advanced considerably from a theoretical and numerical viewpoint that of tests in sands still relies largely on empirical correlations. A major source of such correlations comes from tests done in calibration chambers (CC), where soil state and properties might be tightly controlled. Calibration chambers are relatively large pieces of equipment, and calibration chamber testing is expensive and time consuming. Moreover, CC tests are performed on freshly reconstituted sands whose fabric may vary from that of natural sand deposits. Hence, correlations developed for one type of sand might not be suitable for another sand deposit. Numerical DEM-based calibration chambers might offer an interesting alternative to the more cumbersome physical tests. This study is the first attempt to perform a three-dimensional DEM-based simulation of cone penetration test. The three-dimensional commercial DEM code (PFC3D) is used to develop Virtual Calibration Chamber CPT (VCC CPT) model. To achieve that objective, several steps were necessary. First, calibration of an analogue discrete material to represent Ticino sand was performed using single-element tests. Afterwards, the mechanical response of the discrete material was further validated by performing additional triaxial tests with different initial conditions. The VCC CPT model was then constructed. Comprehensive dimensional analysis showed that the best option to balance computational efficiency and realism was to fill the chamber with a scaled-up calibrated discrete material. An original filtering technique was proposed to extract steady state cone resistances. A basic series of simulations was performed to explore the effect of initial stress and relative density in cone resistance. The results obtained from the simulations did fit closely the trends that had been previously established using physical chambers. That result was taken as a general validation of the proposed simulation approach. From the micromechanical point of view, the granular material is highly discontinuous and inhomogeneous. Obtaining a homogeneous initial state (especially in the zone of the penetrating cone) is crucial to obtain easily interpretable results. Specific procedures to assess initial state inhomogeneities were developed. DEM-based models can provide results at various level of resolution i.e. the microscale, the meso-scale and the macro-scale. A large series of VCC CPT has been performed. Simulations were performed for models with different horizontal servo-control walls, various sizes of chamber, cone and particles and two boundary conditions. The results were analyzed, focusing on aspects such as chamber size, particle size and boundary condition effects on steady state cone resistance values. A smaller number of tests have also been examined from the point of view of shaft resistance. Most trends and results obtained are shown to be in agreement with previous physical tests. When disagreements appear, the causes are identified: the most severe disagreements result from initial inhomogeneities in the discrete model. The work described in this thesis showed ease the burden of future CPT calibrations in granular materials.

    Los ensayos de penetración estática de cono (CPT) son una de las herramientas más importantes en el reconocimiento geotécnico. La interpretación de los resultados de ensayo en arcilla ha avanzado considerablemente desde un punto de vista teórico y numérico. Sin embargo la interpretación de los resultados en los materiales granulares por ejemplo arena) todavía está basada en correlaciones empíricas provenientes de las pruebas realizadas en cámaras de calibración (CC), donde el estado del suelo y sus propiedades pueden ser controlados. Las cámaras de calibración son equipos relativamente grandes, y los ensayos en ellas son bastante costosos en tiempo y recursos. Por otra parte, las pruebas se realizan en muestras de arenas reconstituidas cuyas propiedades varían respecto de los depósitos naturales de donde provienen. Por lo tanto, las correlaciones desarrolladas en un tipo de arena podrían no ser adecuadas para otro depósito distinto. Cámaras de calibración numéricas (virtuales) basadas en el método de elementos discretos (DEM) podrían ofrecer una alternativa interesante a los ensayos físicos. Este estudio es el primer intento de realizar una simulación basadas en el método de los elementos discretos tridimensionales de ensayos de penetración de cono. El código comercial tridimensional (PFC3D) ha sido usado para desarrollar el modelo de CPT de Cámara de Calibración Virtual (CPT VCC). Para alcanzar este objetivo fueron necesarios varios pasos. En primer lugar, se llevó acabo la calibración de un material discreto análogo a arena de Ticino mediante ensayos elementales. A continuación se construyó el modelo CPT VCC. Un análisis dimensional exhaustivo mostró que la mejor opción para crear un modelo eficiente y real era llenar la cámara con un material con el tamaño de grano 50 veces mayor que el de la arena de Ticino. Se propuso una técnica original de filtrado para extraer la resistencia de punta estacionaria. Se realizó una serie básica de simulaciones para explorar el efecto de la tensión inicial y la densidad relativa sobre la resistencia de cono. Los resultados obtenidos de las simulaciones se ajustan estrechamente a las tendencias establecidas previamente en cámaras físicas. Este resultado fue tomado como una validación general del programa de simulación propuesto. Desde el punto de vista de la micro-mecánica, el material granular es muy discontinuo y no homogéneo. La obtención de un estado inicial homogéneo (especialmente en la zona de penetración del cono) es crucial para obtener resultados fácilmente interpretables. Por lo tanto se han desarrollado procedimientos específicos para evaluar heterogeneidades del estado inicial. Los resultados manifestaron el papel clave del contorno de modelo (paredes rígidas), tanto pasivo como activo (servo-controlados), durante la formación del modelo. Los modelos basados en el DEM puede proporcionar resultados a varios niveles de la resolución, es decir del micro-, meso- y macro escala. Se ha realizado una gran serie de VCC CPT. Las simulaciones se realizaron para modelos con diferentes posiciones en las paredes horizontales de servo-control, varios tamaños de cámara, varios tamaños del cono y de las partículas y dos condiciones de contorno. Los resultados se analizaron centrándose en varios aspectos como el tamaño de la cámara, el tamaño de las partículas y los efectos de condiciones de contorno sobre el valor de la resistencia de punta. Un número limitado de los CPT fue examinado desde el punto de vista de la resistencia del fuste del cono. Se observó que la mayoría de las tendencias y los resultados obtenidos estaban de acuerdo con resultados previos obtenidos en ensayos físicos. El trabajo presentado en esta tesis debería facilitar futuras calibraciones CPT en materiales granulados.

  • Abrasivity measures on geotechnical materials of the Barcelona area

     Gonzalez Gonzalez, Juan Carlos; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    ISRM European Rock Mechanics Symposium
    p. 345-350
    DOI: 10.1201/b16955-56
    Presentation's date: 2014-05-26
    Presentation of work at congresses

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    Cutting tool replacement and maintenance operations might take up to a quarter of the total active time on mechanized tunnel excavation. Tool wear estimation is therefore necessary for accurate planning and costing of such operations. One of the main factors affecting tool replacement rates is abrasivity. Abrasivity is a property of geomaterials that quantifies their ability to cause wear on the tools interacting with them. There are several index tests (e.g. CAI) that are in use to quantify abrasivity. However, most of them are inappropriate when the tunnel operation passes through soils and rocks. In this communication we present a methodology applied to obtain a uniform measure of abrasivity for all the geotechnical units encountered on 23 km of tunnels recently perforated in the Barcelona area with different EPBs machines. The geotechnical conditions encountered were very heterogeneous, ranging from soft soils to hard and medium rocks, and frequently resulting in mixed soil-rock conditions. LCPC-type abrasivity measurements were obtained in all the materials.A descriptive summary of the main trends revealed by the data is presented. The ability of this test to evaluate abrasivity in all circumstances is highlighted by comparison with the more limited results achieved when applying other measurement methods

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     Arroyo Alvarez de Toledo, Marcos
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  • Grupo de Geotecnia y Mecánica de Materiales

     Carol Vilarasau, Ignacio; Gens Sole, Antonio; Josa Garcia-tornel, Alejandro; Ledesma Villalba, Alberto; Lloret Morancho, Antonio; Olivella Pastalle, Sebastian; Prat Catalan, Pere; Romero Morales, Enrique Edgar; Vaunat, Jean; Lopez Garello, Carlos Maria; Arroyo Alvarez de Toledo, Marcos; Pinyol Puigmarti, Nuria Merce; Rodriguez Dono, Alfonso; Alonso Pérez de Agreda, Eduardo
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  • Shallow foundations for offshore wind towers

     Arroyo Alvarez de Toledo, Marcos; Abadías, D.; Alcoverro, J.; Gens Sole, Antonio
    International Conference on Soil Mechanics and Geotechnical Engineering
    p. 2303-2306
    Presentation's date: 2013-09
    Presentation of work at congresses

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    Direct foundations are present in about 25% of the installed offshore wind power towers. The peculiarities of this type of structure are well known: high dynamic sensitivity, complex couplings between environmental actions, machine operation and structural response, complex installation and maintenance, difficult site investigation. There is a clear need for optimized foundation design tools that would enable cost reduction and a more detailed assessment of the risk of every installation. One such tool is likely to be the systematic use of failure envelopes for capacity checks. The paper explores the benefits of such an approach with various realistic design examples.

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    THMC modelling of jet grouting  Open access

     Gesto, Jose M; Gens Sole, Antonio; Arroyo Alvarez de Toledo, Marcos
    International Conference on Computational Plasticity Fundamentals and Applications
    p. 1353-1359
    Presentation's date: 2013-09
    Presentation of work at congresses

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    A framework for the study of the jet-grouting hydration reaction and of the associated thermo-hydro-mechanical and chemical (THMC) interactions with the surrounding soils has been developed. In this work, we summarize the basic formulation that may be used for the simulation of such interactions, including references to the balance equations governing the problem, to the release of heat during the curing of the jet-grouted mass, to the TMC behaviour of such material and to the THM behaviour of the surrounding soil. The approach presented falls within the framework of plasticity for saturated soils, and it has been implemented within a FEM code for the study of the potential effects of the THMC couplings associated to jet-grouting treatments. The results obtained with this program validate it as a proper tool for the systematic analysis of a number of questions of interest in engineering practice, allowing the assessment, among others, of the following issues: magnitude and rate of production of the thermo-plastic settlements caused by the heat release associated to the installation of jet-grouted columns in the soil; effects of the release of the hydration heat on the hydraulic conditions in the surrounding soil; effects of the boundary conditions, the relative position of the jet-grouted zones and its sequence of installation on the rate of increase of the stiffness and strength associated to the curing of the jet-grouted zones; effects of those factors on the impact of the heat release on the surrounding soils.

  • The effect of radial walls on CPT in a DEM-based virtual calibration chamber

     Arroyo Alvarez de Toledo, Marcos; Butlanska, Joanna; Gens Sole, Antonio; O'Sullivan, Catherine
    International Symposium on Computational Geomechanics
    p. 186-195
    Presentation's date: 2013-08
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  • A practical method for suction estimation in unsaturated soil testing

     Amaral, Miguel F.; Viana da Fonseca, A.; Romero Morales, Enrique Edgar; Arroyo Alvarez de Toledo, Marcos
    Pan-American Conference on Unsaturated Soils
    p. 185-189
    Presentation's date: 2013-02
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    This research presents an alternative methodology to estimate suction in triaxial tests carried out under constant water content. A preliminary determination of the retention curve is proposed using two complementary techniques, namely psychrometer measurements and mercury intrusion porosimetry results. Starting with the definition of a set of retention curves at different void ratios, an attempt is made for establishing a correspondence of the measured retention curves with the results of a high pressure isotropic compression test. From the stress-paths followed in a soil-cement specimen during isotropic compression, plotted in the void ratio-stress plane, the suction is interpolated by using the previously measured values and the evolution law describing suction as a function of the specimen's void ratio. For the aforementioned paths, the suction for all stress state points is estimated, including for the apparent yield pressure

    This research presents an alternative methodology to estimate suction in triaxial tests carried out under constant water content. A preliminary determination of the retention curve is proposed using two complementary techniques, namely psychrometer measurements and mercury intrusion porosimetry results. Starting with the definition of a set of retention curves at different void ratios, an attempt is made for establishing a correspondence of the measured retention curves with the results of a high pressure isotropic compression test. From the stress-paths followed in a soil-cement specimen during isotropic compression, plotted in the void ratio-stress plane, the suction is interpolated by using the previously measured values and the evolution law describing suction as a function of the specimen’s void ratio. For the aforementioned paths, the suction for all stress state points is estimated, including for the apparent yield pressure.

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     Arroyo Alvarez de Toledo, Marcos
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  • CARACTERIZAÇÃO E MODELAÇÃO DE COMPORTAMENTO DINÂMICO E CÍCLICO DE MISTURAS DE SOLO-CIMENTO PARA INFRAESTRUTURAS DE TRANSPORTES

     MIGUEL FRANCISCO SILVA SOUSA FERREIRA DO AMARAL
    Faculdade de Engenheria, Universidade do Porto
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  • Sensitivity to damping in sand production DEM-CFD coupled simulations

     Climent Pera, Natalia; Arroyo Alvarez de Toledo, Marcos; O'Sullivan, Catherine; Gens Sole, Antonio
    International Conference on Micromechanics of Granular Media
    p. 1170-1173
    DOI: 10.1063/1.4812145
    Presentation's date: 2013
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    A three dimensional numerical model based on Discrete Element Method (DEM) and coupled with Computational Fluid Dynamics (CFD) was implemented to simulate sand production. Simulations with no fluid flow conditions and with fluid flow conditions have been performed and the sensitivity of the simulations to numerical damping is studied.

  • Numerical simulation of THMC phenomena associated with jet-grouting

     Gesto, José; Gens Sole, Antonio; Arroyo Alvarez de Toledo, Marcos
    International Conference on Ground Improvement and Ground Control
    p. 1121-1127
    Presentation's date: 2012-11
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    A framework for the study of the jet-grouting hydration reaction and of the associated THMC interactions with the surrounding soils has been developed. In this work, we summarize the basic formulation that may be used for the simulation of such interactions, including references to the balance equations governing the problem, to the release of heat during the curing of the jet-grouted mass, to the TMC behavior of such material and to the THM behavior of the surrounding soil. The approach presented falls within the framework of plasticity for saturated soils, and it has been implemented within a FEM code for the study of the potential effects of the THMC couplings associated to jet-grouting treatments. The results obtained with this program validate it as a proper tool for the systematic analysis of a number of questions of interest in engineering practice, allowing the assessment, among others, of the following issues: magnitude and rate of production of the thermo-plastic settlements caused by the heat release associated to the installation of jet-grouted columns in the soil; effects of the release of the hydration heat on the hydraulic conditions in the surrounding soil; effects of the boundary conditions, the relative position of the jet-grouted zones and its sequence of installation on the rate of increase of the stiffness and strength associated to the curing of the jet-grouted zones; effects of those factors on the impact of the heat release on the surrounding soils.

  • 3D DEM simulations of CPT in sand

     Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    International Conference on Geotechnical and Geophysical Site Characterization
    p. 817-824
    Presentation's date: 2012-09
    Presentation of work at congresses

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    The paper contains an overview of the results obtained in a research project exploring the ability of 3D DEM models to reproduce cone penetration in sands. The sand whose behaviour is mimicked by the discrete material is Ticino sand, a well known reference material for cone penetration tests. A large series of numerical experiments in a cylindrical virtual calibration chambers was performed in materials of medium and high density. Point resistance is shown to fit well with results from previous physical tests when the various scaling factors affecting the problem are taken into account. The effect of different boundary conditions on the test results is illustrated. The appearance of friction fatigue in the shaft resistance is also revealed by the analysis of the numerical results. The micromechanics of cone penetration is also illustrated, showing that a stationary condition is clearly attained for point/soil contacts and how particle flow is affected by boundary conditions. From the results presented it can be inferred that 3D DEM simulations offer a feasible alternative to extend and/or partially substitute the more expensive physical calibration tests in the development of CPT based correlations, as well as powerful capabilities to explore the micromechanics of the problem.

  • Site characterization alternatives for numerical models of a deep excavation

     Sau, Núria; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    International Conference on Geotechnical and Geophysical Site Characterization
    p. 1169-1177
    Presentation's date: 2012-09
    Presentation of work at congresses

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    A cut-and-cover railway tunnel site on the outskirts of Barcelona benefited from an extensive site investigation campaign. During the construction of the tunnel, the displacement of the wall as well as the of soil beneath was recorded. A 2D numerical model of the excavation sequence was established. The large amount of site investigation data allowed a systematic comparative approach. Four different soil characterization strategies were mimicked, deliberately ignoring one or another subset of the characterization data. While results from CPTu and SPT were assumed equally available to all the hypothetical designers, the extra information for one of them was only laboratory test results, for another one it was pre-bored PMT data, for the third one it was SBPM and cross-hole tests data and, finally, the last one had DMT, SDMT and cross-hole tests data as complementary information. The simulation results are obtained using the Hardening soil model.

  • Testing block samples from silty deposits

     Pineda Jimenez, Jubert Andrés; Arroyo Alvarez de Toledo, Marcos; Sau Valenzuela, Núria; Gens Sole, Antonio; Pérez, Norma
    International Conference on Geotechnical and Geophysical Site Characterization
    p. 1815-1823
    Presentation's date: 2012-09
    Presentation of work at congresses

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    The paper describes the results of a comprehensive experimental program aimed to characterize block samples of silty deposits obtained from the deltaic zone of the Llobregat River ( Barcelona).Undisturbed block samples were obtained from a deep excavation taking place on interbedded sandy silts by hand retrieval. A detailed examination of the retrieved blocks, including suction measurements as well as Computed Axial Tomography (CAT) scans was performed before testing. Material characterization was complemented with identification tests carried out on representative samples obtained at different points inside the block. Finally, soil disturbance was evaluated by means of CRS oedometer tests on specimens retrieved at different depths. The spatial variability of suction (water potential) and water content was defined here based on tensiometer measurements. From CAT images the sedimentary nature of the block as well as the position and 3D distribution of heterogeneities could be detected. CRS tests showed a similar stress-strain response from which the evaluation of sample disturbance indicated the very high quality of samples tested.

  • Testing a new submersible drill rig

     Romero, F.; Devincenzi, M.J.; Pérez Garcia, N.; Arroyo Alvarez de Toledo, Marcos; Deu Lozano, Amadeu
    International Conference Offshore Site Investigation and Geotechnics
    p. 245-252
    Presentation's date: 2012-09
    Presentation of work at congresses

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    The paper describes the main features and initial underwater field-testing results of a remotely operated submersible drill rig designed to obtain continuous cores of soil and/or rock up to 6m long in water depths of 200m. The rig mast angle is hydraulically actuated covering 90° of altitude. This enables both a fully horizontal position used for deployment onto, and recovery of the rig from, the seabed, as well as a fully vertical position during coring. The frame is equipped with positioning and inclination sensors for accurate register of core orientation. Coring equipment with diameter of up to 133mm can be mounted in the rig, thus enabling the recovery of relatively large-diameter cores. The coring operation is fully instrumented and all the drill operation parameters such as torque, thrust, advance, injection rate and pressure are recorded. The equipment is deployable from a variety of platforms.

  • A submersible drill rig for coring soils and rocks

     Devincenzi, M.J.; Pérez Garcia, N.; Samoili, K.; Arroyo Alvarez de Toledo, Marcos
    International Conference on Geotechnical and Geophysical Site Characterization
    p. 653-658
    Presentation's date: 2012-09
    Presentation of work at congresses

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    The paper describes the design and initial field-testing of a remotely operated submersible drill rig able to obtain continuous cores of soil and/or rock up to 6 m long. The rig mast angle is hydraulically actuated covering 90 degrees of altitude. This enables both a fully horizontal position used for deployment onto and recovery of the rig from the seabed, as well as a fully vertical position during coring. The frame is equipped with positioning and inclination sensors for accurate register of core orientation. Coring equipment with diameter of up to 133 mm can be mounted in the rig, thus enabling the recovery of relatively large-diameter cores. The coring operation is fully instrumented and all the drill operation parameters like torque, thrust, advance, injection rate and pressure are recorded. The equipment is adapted for geotechnical investigation of the renewable energy industry, as well as pipelines, cables and dredging requiring platform or near shore site investigation. The equipment is deployable from a variety of platforms and does not require a fully-fledged drill ship.

  • Modelling of Jet Grouting and its interactions with surrounding soils

     Gesto, José; Gens Sole, Antonio; Arroyo Alvarez de Toledo, Marcos
    International Symposium on Coupled Phenomena in Environmental Geotechnics
    p. 247-256
    Presentation's date: 2012-06
    Presentation of work at congresses

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    The versatility of Jet-Grouting as a soil improvement technique has made this procedure to be widely used in geotechnical engineering practice. In this work we discuss some aspects related to the THMC coupling phenomena that may arise when the Jet-Grouting technique is employed. Namely, we describe some basic constitutive models that may be appropriate to simulate the response of the surrounding soils and that of the Jet-Grouted soil itself while those interactions take place.

  • GEOHAZARDS AND GEOMECHANICS

     Arroyo Alvarez de Toledo, Marcos
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  • Conminución granular y resistencia de interfase: aplicación da los pilotes off-shore

     Gesto Beiroa, Jose Manuel; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
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  • Cimentación directa para eólica marina

     Arroyo Alvarez de Toledo, Marcos; Alcoverro, Jordi; Abadías, David; Gens Sole, Antonio
    Simposio Nacional de Ingeniería Geotécnica
    p. 63-86
    Presentation's date: 2012
    Presentation of work at congresses

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  • Design control and monitoring of a jet grouted excavation bottom plug

     Eramo, N.; Modoni, Giuseppe; Arroyo Alvarez de Toledo, Marcos
    International Symposium TC28
    p. 611-618
    Presentation's date: 2012
    Presentation of work at congresses

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    Jet grouting is adopted in different geotechnical conditions to ensure provisional earth retaining and waterproofing functions at the bottom and walls of excavations. Despite careful theoretical models avail-able to predict the mechanical response of these structures, design is often carried out without adequate con-trol, i.e. by assuming ideal effectiveness of ground improvement. On the contrary, adverse effects have been documented by past experiences which can be traced back to erroneous prediction of treatments effects, inac-curate control of the execution or to unexpected responses of the surrounding environment. All these uncertainties, which become particularly critical when excavation is performed in urbanized areas, can be mini-mized by detailed preliminary field trials, accurate controls of the execution of treatments and a prompt monitoring of the surrounding area. The present paper describes this methodology applied to the design and the execution of a massive jet grouting bottom plug forming the base of a large excavation in city environment. The results of preliminary field trials are summarized to directly compare the effectiveness of different injection systems and introduced in statistical design analyses of the jet grouted structure. A detailed investigation of the movements induced at ground level by injections is also reported. To this aim, the evolution of displacements recorded around trial columns and on the area surrounding the excavation is mapped to evaluate the effects of the different adopted injection techniques.

  • Estrategias alternativas de caracterización geomecánica para el análisis numérico de excavaciones apantalladas

     Sau, N.; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    Simposio Nacional de Ingeniería Geotécnica
    p. 835-846
    Presentation's date: 2012
    Presentation of work at congresses

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  • Development of a family of constitutive models for Geotechnical Applications

     González Molano, Nubia Aurora
    Department of Geotechnical Engineering and Geo-Sciences, Universitat Politècnica de Catalunya
    Theses

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  • Modelling the behaviour of structured London Clay

     González, N.A.; Gens Sole, Antonio; Arroyo Alvarez de Toledo, Marcos; Rouainia, Mohamed
    International Symposium on Deformation Characteristics of Geomaterials
    p. 1052-1059
    Presentation's date: 2011-09
    Presentation of work at congresses

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    The paper presents a constitutive modelling of the London clay based on the detailed laboratory knowledge gathered about London clay structure (Hight et al, 2007; Gasparre et al, 2007; Gasparre & Coop, 2008). Modelling was performed using a structured kinematic hardening soil model based on Rouainia & Wood (2000). It was found that a smooth elasto-plastic transition was required to avoid a spurious stiffness degradation response. Consequently, the initial model was modified following a procedure similar to that suggested by Grammatikopoulou et al. (2006). Parameters associated with soil structure and state variables for each lithological sub-unit of the London clay are presented. A good prediction of stress-strain, strength and stiffness behaviour in the small strain range is obtained in spite of the complex behaviour observed in laboratory. The significantly different mechanical behaviours of the lithological sub-units, arising from differences in structure, are adequately reproduced.

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    A structured constitutive model for simulating the behaviour of an overconsolidated bonded clay  Open access

     González, Nubia; Gens Sole, Antonio; Arroyo Alvarez de Toledo, Marcos; Rouainia, Mohamed
    International Conference on Computational Plasticity Fundamentals and Applications
    p. 2-12
    Presentation's date: 2011-09
    Presentation of work at congresses

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    The paper presents some improvements in the formulation of a kinematic hardening constitutive soil model incorporating structure initially proposed for soft clays. For the modelling of overconsolidated bonded clay the elastic formulation was deemed more important. Two different alternatives, one purely empirically based the other with a background in thermodynamics were implemented. It was also found that a smooth elasto-plastic transition was required to avoid a spurious stiffness degradation response. Consequently, the hardening modulus formulation of the model was modified. The paper presents some results from a parametric analysis of the triaxial drained response of a material tailored to mimic London clay. The results chosen do not show a major difference between the chosen alternative elastic formulations, although both do improve the original model response. On the other hand the importance of ensuring a smooth elasto-plastic transition is clearly highlighted.

  • Design of jet-grouting for tunnel waterproofing

     Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio; Croce, Paolo; Modoni, Giuseppe
    International Symposium TC28
    p. 181-188
    Presentation's date: 2011-05
    Presentation of work at congresses

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    A case history in Barcelona is described where a tunnel was excavated by traditional methods below an active railway line through a formation with lenses of water-bearing granular material. To avoid the possibility of sudden collapses a massive jet-grout treatment was applied. The treatment took several forms. Subvertical double and triple-fluid injection was applied whenever possible. Sub-horizontal monofluid canopies and slabs executed from within the tunnel were however required in zones where no vertical access was possible. This communication focuses on the later type of treatments and gives an overview of the design tools that were applied. These comprised the execution of several large trial fields and the systematic application of a probabilistic framework for design.

  • The influence of jet-grout constitutive modelling in excavation analyses

     Ciantia, Matteo; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio; Castellanza, Riccardo
    International Symposium TC28
    p. 773-780
    Presentation's date: 2011-05
    Presentation of work at congresses

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    A bonded elasto-plastic soil model is employed to characterize cement-treated clay in the finite element analysis of an excavation on soft clay supported with a soil-cement slab at the bottom. The soft clay is calibrated to represent the behaviour of Bangkok soft clay. A parametric study is run for a series of materials characterised by increasing cement content in the clay-cement mixture. The different mixtures are indirectly specified by means of their unconfined compressive strength. A similar parametric analysis is run in parallel using a linear elastic-perfectly plastic model for the clay-cement. Results from both series of analysis are compared highlighting the differences in predicted behaviour of the retaining wall and the excavation stability.

  • Triaxial and cone penetration tests in a discrete analogue of Toyoura sand

     Climent Pera, Natalia; Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    International FLAC/DEM Symposium
    p. 1-4
    Presentation's date: 2011
    Presentation of work at congresses

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  • A soft-rock model for cement-improved clays

     Arroyo Alvarez de Toledo, Marcos; Ciantia, Matteo; Gens Sole, Antonio; Castellanza, Riccardo
    European Conference on Soil Mechanics and Geotechnical Engineering
    p. 501-506
    Presentation's date: 2011
    Presentation of work at congresses

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  • Mapping deformation during CPT in a virtual calibration chamber

     Butlanska, Joanna; O'Sullivan, Catherine; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    International Symposium on Geomechanics and Geotechnics
    p. 559-564
    Presentation's date: 2010-10
    Presentation of work at congresses

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    This paper analyses results from a three dimensional discrete element method simulation of the cone penetration test in a "Virtual Calibration Chamber" (VCC). The deformation patterns in the soil adjacent to the cone during penetration are considered. While some insight can certainly be achieved by visualization of the discrete particle displacements, typically in geomechanics our interpretations of material response are in terms of (continuum) strains. Here a local, non-linear, wavelet based approach is used to calculate the strain distribution within the VCC. This method was found to represent effectively strain fields as penetration proceeds. The axial symmetry of the system at the macro level is c1early evidenced by the strain plots.

  • Size effects on a virtual calibration chamber

     Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    European Conference on Numerical Methods in Geotechnical Engineering
    p. 225-230
    Presentation's date: 2010-06
    Presentation of work at congresses

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    Virtual Calibration Chambers (VCC) are 3D-DEM models where cone penetration is simulated. They offer the possibility of substituting for the rather more expensive physical calibration chambers. One important issue in calibration chamber interpretation is the possibility of chamber size effect under different boundary conditions. The aim of this study was to explore chamber size effects under BC1 and BC3 conditions on the VCC. The chamber and cone diameters and boundary conditions were varied to investigate their effects on cone tip resistance. The scaling laws that are obtained from the VCC results are then compared with those previously obtained with physical calibration chambers.

  • Analysis of ground movements induced by diaphragm wall installation

     Garitte, Benoit; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    European Conference on Numerical Methods in Geotechnical Engineering
    p. 547-552
    Presentation's date: 2010-06
    Presentation of work at congresses

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    The construction process of diaphragm walls can lead to movements in the surrounding area that are seldom taken into account. However, these movements may be important in situations where soft soils dominate. In this paper, after briefly reviewing the state of the art on this issue, we present results of a hydromechanical simulation of the problem in a case located in deltaic soils of Barcelona. The auscultation record of the settlements of a nearby building is employed to validate the computational model. Panel length and bentonite slurry level were found to be the most influent parameters on induced displacements.

  • Virtual Calibration Chamber CPT on Ticino sand

     Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    International Symposium on Cone Penetration Testing
    p. 217-224
    Presentation's date: 2010-05
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    The following paper surnmarizes results of CPT's performed in virtual calibration chamber (VCC) built with a 3D model based on the distinct element method (DEM). A discrete material tailored to mimic Ticino sand is tested at different densities, stress and stress history. The limit cone tip resistance from the numerical experiments shows quantitative agreement with different empirical curves summarizing previous tests on Ticino sand in physical calibration chambers (ENEL and ISMES).

  • MUESTREO GEOTECNICO DE ALTA CALIDAD EN SUELOS BLANDOS

     Pineda Jimenez, Jubert Andrés; Arroyo Alvarez de Toledo, Marcos
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  • Valoration technique des structures en sol traitées par jet grouting

     Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    International Society for Soil Mechanics and Geotechnical Engineering
    p. 2338-2341
    DOI: 10.3233/978-1-60750-031-5-2338
    Presentation's date: 2009-10-07
    Presentation of work at congresses

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    The treatment characteristics, quality control measures and outcomes of two different jet-grout based soil treatments are described in detail. In the first one, a jet-grouted slab was built to limit retaining wall movements in a cut-and-cover tunnel. Quality control relied on borehole core quality assessment and laboratory testing. Core quality was very sensitive to coring practices. The strength and stiffness of the jet-grouted slab were deemed adequate and the structure successfully contributed to minimal wall movements. In the second case, a jet-grouted treatment was designed to provide strengthening and impermeabilization around a tunnel excavated on silty sands below the water table and underneath another tunnel. Control was based on extensive coring, cross-hole seismic surveys and permeability tests. The results were generally favourable and where defects were detected, reparation was undertaken. However, in spite of all those actions, a number of deficiencies escaped detection and only became apparent during the excavation of the tunnel resulting in significant construction problems./ /Les caractéristiques de traitements, les mesures de contrôle de qualité et les résultats de deux différents traitements de sol par jet grouting sont expliqués en détail. Dans l’un d’entre eux, on a construit une plaque par jet grouting pour limiter les mouvements des parois de soutènement d’une tranchée recouverte. Le contrôle de qualité s’appuyait sur l’évaluation de la qualité des carottes de sondage et des tests de laboratoire. La qualité des carottes était très sensible à la méthodologie de forage. La résistance et la rigidité de la plaque par jet grouting ont été considérées adéquates et la structure a contribué avec succès à limiter les mouvements de parois. Dans l’autre cas, un traitement par jet grouting a été conçu pour renforcer et imperméabiliser la zone autour d’un tunnel excavé dans des sables limoneux plus bas que le niveau phréatique et en-dessous d’un autre tunnel. Le contrôle était basé sur de nombreux forages, de la sismique cross-hole et des tests de perméabilité. Les résultats étaient généralement favorables et les défauts détectés ont été réparés. Malgré tous ces efforts, un certain nombre d’imperfections ont échappé à la détection et sont seulement devenus apparents lors de l’excavation du tunnel ce qui a produit des problèmes de construction significatifs.

  • GRUPO DE GEOTECNIA Y MECANICA DE MATERIALES

     Levatti, Hector Ulises; Carol Vilarasau, Ignacio; Olivella Pastalle, Sebastian; Lopez Garello, Carlos Maria; Gens Sole, Antonio; Vaunat, Jean; Prat Catalan, Pere; Lloret Morancho, Antonio; Rodriguez, Mariana; Butlanska, Joanna; Garitte, Benoit; Ramon Tarragona, Anna; Jacinto, Carlos Abel; Aliguer Piferrer, Ignasi; Yubero De Mateo, Maria Teresa; Romero Morales, Enrique Edgar; Gesto Beiroa, Jose Manuel; Tapias Camacho, Mauricio Alberto; Garolera Vinent, Daniel; Lakashmikhanta, Ramasesha; Ledesma Villalba, Alberto; Pineda Jimenez, Jubert Andrés; Arroyo Alvarez de Toledo, Marcos; Josa Garcia-tornel, Alejandro; Sanchez Carracedo, Fermin; Pinyol Puigmarti, Nuria Merce; De Santos Rodriguez, Cristian; Alonso Pérez de Agreda, Eduardo
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  • MODELACION GEOTECNICA AVANZADA DE TRATAMIENTOS DEL TERRENO POR EROSION Y MEZCLA.APLICACION AL JET-GROUTING

     Olivella Pastalle, Sebastian; Vaunat, Jean; Arroyo Alvarez de Toledo, Marcos; Garitte, Benoit; Gens Sole, Antonio
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  • Influence of some EPB operation parameters on ground movements

     Di Mariano, Alessandra; Persio, Roberto; Gens Sole, Antonio; Castellanza, Riccardo; Arroyo Alvarez de Toledo, Marcos
    International Conference on Computational Methods in Tunnelling
    p. 43-49
    Presentation's date: 2009
    Presentation of work at congresses

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    Some of the details of EPB tunnelling are difficult to introduce in conventional numerical models, nevertheless there are some parameters that can be included in the analyses in a fairly easy way. The EPB operating pressures are examples of these parameters. In this paper, the influence of such pressures on the ground movements and volume losses is examined. The construction of one of Barcelona Line 9 tunnels is taken as the reference case study. It is a 9.40 m diameter tunnel excavated in soft deltaic materials, below the ground water level

  • Homogeneity and symmetry in DEM models of cone penetration

     Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    International Conference on the Micromechanics of Granular Media
    p. 425-428
    Presentation's date: 2009
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    A three—dimensional numerical model was implemented to PFC3D Code to simulate cone penetration test in Ticino sand in a calibration chamber. The model is calibrated using laboratory test results. The full/half/quarter calibration chamber was used to examine the effect of symmetry on the results. Examination of specimen homogeneity was done by (i) visual observation of the network of the contact forces developing between particles, (ii) examination of the porosity, d50 and Cu distributions inside the specimen by using a representative elementary volume (REV). Some overall results from these simulations are also presented here and compared with the experimental results from a calibration chamber test database.

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    Effects of heating and hydraulic cycling on the stiffness response of a rigid ansiotropic clay: preliminary results  Open access

     Mitaritonna, Giuseppina; Pineda Jimenez, Jubert Andrés; Romero Morales, Enrique Edgar; Arroyo Alvarez de Toledo, Marcos
    Deformation and failure of geomaterials. A Multidisciplinary Scientific Workshop
    Presentation's date: 2009
    Presentation of work at congresses

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    The poster presents the results of an experimental investigation aimed at evaluating the effects of heating and hydraulic cycling on the small-strain stiffness of a rigid Jurassic clay (Opalinus clay, Jura Mountains, Mont Terri Underground Laboratory, Switzerland). This clay was subjected to thermal loads during an in situ heating experiment (HE-D). After the test, intact samples were retrieved and analysed at laboratory scale. The influence of thermal loads was studied using basic characterisation, microstructural techniques (MIP) and non-destructive techniques (ultrasonic pulses). The retrieved samples were then subjected to wetting and drying paths. The hydraulic effects were tracked using basic characterisation (water content and porosity) and non-destructive techniques (ultrasonic pulses and bender elements). Test results showed a higher sensitivity of stiffness on suction increase for the material less affected by the thermal load (far from heater). Tests are currently being carried out on a new and fully instrumented high-pressure triaxial cell to monitor degradation effects induced by hydraulic cycling under a controlled stress field. Degradation is monitored by horizontal and vertical bender elements to track different directions.

    Postprint (author’s final draft)

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    The effect of drying-wetting cycles on the seismic properties of an anisotropic claystone  Open access

     Mitaritonna, Giuseppina; Pineda Jimenez, Jubert Andrés; Arroyo Alvarez de Toledo, Marcos; Romero Morales, Enrique Edgar
    Biot Conference on Poromechanics
    p. 1-8
    Presentation's date: 2009
    Presentation of work at congresses

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    The evolution of bar and shear wave velocities during a drying wetting cycle on a claystone is presented. There is a clear relationship with total suction, established by means of the material water retention curve. The stiffening effect of drying decreases with sample damage. The multiaxial bender element technique is firstly applied to rocklike materials with partial success.

    Postprint (author’s final draft)

  • La simulación numérica y el ensayo presiométrico

     Arroyo Alvarez de Toledo, Marcos
    Date of publication: 2008-06
    Book chapter

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  • Informe anual

     Gens Sole, Antonio; Arroyo Alvarez de Toledo, Marcos
    Date: 2008-03
    Report

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  • Dynamic tracking of hydraulically induced claystone degradation

     Pineda Jimenez, Jubert Andrés; Arroyo Alvarez de Toledo, Marcos; Romero Morales, Enrique Edgar; Alonso Pérez de Agreda, Eduardo
    International Symposium on Deformation Characteristics of Geomaterials
    p. 809-817
    Presentation's date: 2008
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  • Precise hydraulic conductivity measurements on tire derived aggregate

     Romero Morales, Enrique Edgar; SanMartin, I; Arroyo Alvarez de Toledo, Marcos; Lloret Morancho, Antonio
    European Geosynthetics Conference
    p. 1-6
    Presentation's date: 2008
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  • SBPM testing in Bothkennar clay: structure effects

     Arroyo Alvarez de Toledo, Marcos; González, N; Butlanska, Joanna; Gens Sole, Antonio; Dalton, C
    International Conference on Site Characterization
    p. 456-462
    Presentation's date: 2008
    Presentation of work at congresses

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    A series of self-boring pressuremeter tests performed in Bothkennar clay are simulated using a finite element model of undrained cavity expansion. A bonded elasto plastic soil model is employed to represent Bothkennar clay behaviour. The model is calibrated using laboratory test results. Then, the pressuremeter expansion curve and the cavity pore pressure curves are predicted, both for tests made at depths where laboratory results are available and for tests where such information is missing. Comparison is made in terms of the whole response curves and of standard field test interpretation. The effect of structure is made explicitly visible by comparing simulations with and without structure. Introducing structure in the model considerably improves the simulation results. This means that SBPM tests seem able to detect most of the original soil structure.