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  • Study of mechanical behavior and strain localization of methane hydrate bearing sediments with different saturations by a new DEM model

     Jiang, Mingjing; Chen, He; Tapias Camacho, Mauricio Alberto; Arroyo Alvarez de Toledo, Marcos; Fang, Rui
    Computers and geotechnics
    Date of publication: 2014-04
    Journal article

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    This paper presents a numerical investigation into mechanical behavior and strain localization in methane hydrate (MH) bearing sediments using the distinct element method (DEM). Based on the results of a series of laboratory tests on the bonded granules idealized by two glued aluminum rods and the available experimental data of methane hydrate samples, a pressure and temperature dependent bond contact model was proposed and implemented into a two-dimensional (2D) DEM code. This 2D DEM code was then used to numerically carry out a series of biaxial compression tests on the MH samples with different methane hydrate saturations, whose results were then compared with the experimental data obtained by Masui et al. [9]. In addition, stress, strain, void ratio and velocity fields, the distributions of bond breakage and averaged pure rotation rate (APR) as well as the evolution of strain localization were examined to investigate the relationships between micromechanical variables and macromechanical responses in the DEM MH samples. The numerical results show that: (1) the shear strength increases as methane hydrate saturation SMH increases, which is in good agreement with the experimental observation; (2) the strain localization in all the DEM MH samples develops with onset of inhomogeneity of void ratio, velocity, strain, APR, and distortion of stress fields and contact force chains; and (3) the methane hydrate saturation affects the type of strain localization, with one shear band developed in the case of 40.9% and 67.8% methane saturation samples, and two shear bands formed for 50.1% methane saturation sample.

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     Arroyo Alvarez de Toledo, Marcos
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  • Isotropic yielding of unsaturated cemented silty sand

     Arroyo Alvarez de Toledo, Marcos; Amaral, Miguel F.; Romero Morales, Enrique Edgar; da Fonseca, Antonio Viana
    Canadian geotechnical journal
    Date of publication: 2013-06
    Journal article

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    Unsaturated cemented soils are frequent both as designed materials and as naturally occurring layers. Both desiccation and cementation act separately as hardening mechanisms, but it is not clear how exactly their effects combine. Do they enhance one another? Are they mutually reinforcing? This study presents results from an experimental campaign aimed at answering these questions. Five different mixtures of soil (a granite saprolite) and cement (with cement contents in the range 0% to 7% on a dry weight basis) are tested in isotropic compression at four different water content levels. Initial void ratio is also controlled, using two initial compaction densities. Loading is performed at constant water content and suction is inferred from a set of water retention curves obtained from parallel psychrometric and pore-size distribution measurements. The range of yield stresses explored in this study covers almost two orders of magnitude and extends up to 7 MPa at suction values of up to 14 MPa. Both desiccation and cementation increase yield stress, but their effects are less marked when both act together, and therefore they are not mutually reinforcing.

  • 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
    Presentation's date: 2013-02
    Presentation of work at congresses

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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.

  • 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
    Presentation's date: 2013
    Presentation of work at congresses

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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.

    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.

  • 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
    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.

  • THMC modelling of jet grouting

     Gesto, Jose M; Gens Sole, Antonio; Arroyo Alvarez de Toledo, Marcos
    International Conference on Computational Plasticity Fundamentals and Applications
    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, C.
    International Symposium on Computational Geomechanics
    Presentation's date: 2013-08
    Presentation of work at congresses

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  • Steady state of solid-grain interfaces during simulated CPT

     Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    Studia Geotechnica et Mechanica
    Date of publication: 2013
    Journal article

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    It has recently been shown (Arroyo et al. [1]) that 3D DEM models are able to reproduce with reasonable accuracy the macroscopic response of CPT performed in calibration chambers filled with sand. However, the cost of each simulation is an important factor. Hence, to achieve manageable simulation times the discrete material representing the sand was scaled up to sizes that were more typical of gravel than sand. A side effect of the scaled-up discrete material size employed in the model was an increased fluctuation of the macro-response that can be filtered away to observe a macroscopic steady-state cone resistance. That observation is the starting point of this communication, where a series of simulations in which the size ratio between penetrometer and particles is varied are systematically analyzed. A micromechanical analysis of the penetrometer¿particle interaction is performed. These curves reveal that a steady state is arrived also at the particle¿cone contact level. The properties of this dynamic interface are independent of the initial density of the granular material.

  • Abrasividad y su influencia en el rendimiento de una excavación mecanizada

     González Paez, Claudia; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    Obras y proyectos. Revista de ingeniería civil
    Date of publication: 2013
    Journal article

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    El empleo de tuneladoras TBM (Tunnel Boring Machine) es cada vez más frecuente aunque su optimización requiere la evaluación precisa de varios riesgos geotécnicos entre ellos, el efecto de la abrasividad del suelo en el coste y planificación de un proyecto dado. El desgaste de las herramientas es más difícil de calcular que el resto de parámetros de la maquinaria, debido a la complejidad de la interacción entre herramienta de corte y terreno. En este trabajo se usan datos de un caso real de túnel en terrenos mixtos suelo-roca para examinar el resultado de varias metodologías de predicción de la penetración de TBM. También se examinan algunas predicciones de desgaste y se describe y aplica un nuevo método para la evaluación de la abrasividad de geomateriales que puede aplicarse tanto a materiales sueltos como a rocas.

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     Arroyo Alvarez de Toledo, Marcos
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  • Simulation of cement-improved clay structures with a bonded elasto-plastic model: A practical approach

     Arroyo Alvarez de Toledo, Marcos; Ciantia, Matteo; Castellanza, Riccardo; Gens Sole, Antonio; Nova, Roberto
    Computers and geotechnics
    Date of publication: 2012-09
    Journal article

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    Engineering practice has usually dealt with the treated soil bodies using simplistic constitutive models (e.g. elastic perfectly-plastic Mohr¿Coulomb). In this paper, a more refined bonded elasto-plastic model is here applied, with emphasis on the ease of calibration. Empirical studies have identified the ratio of cement content to the cured mixture void ratio as a controlling variable for mechanical response. This observation is elaborated upon to show that measuring porosity and unconfined compressive strength is enough to initialize the state variables of a bonded elasto-plastic model. Data from cement-improved Bangkok clay is employed to illustrate and validate the calibration procedure proposed. The structure-scale consequences of the constitutive model choice for the soil¿cement are explored through the parametric analysis of an idealized excavation problem. A treated soil¿cement slab is characterized by increasing cement contents in the clay¿cement mixture. Two sets of parametric analysis are run characterizing the clay¿cement either with a linear elastic-perfectly plastic model or with the bonded elasto-plastic model. The same values of unconfined compressions strength (UCS) are specified for the two models to make comparisons meaningful. Results from both series of analysis are compared highlighting the differences in predicted behaviour of the retaining wall and the excavation stability.

    Engineering practice has usually dealt with the treated soil bodies using simplistic constitutive models (e.g. elastic perfectly-plastic Mohr–Coulomb). In this paper, a more refined bonded elasto-plastic model is here applied, with emphasis on the ease of calibration. Empirical studies have identified the ratio of cement content to the cured mixture void ratio as a controlling variable for mechanical response. This observation is elaborated upon to show that measuring porosity and unconfined compressive strength is enough to initialize the state variables of a bonded elasto-plastic model. Data from cement-improved Bangkok clay is employed to illustrate and validate the calibration procedure proposed. The structure-scale consequences of the constitutive model choice for the soil–cement are explored through the parametric analysis of an idealized excavation problem. A treated soil–cement slab is characterized by increasing cement contents in the clay–cement mixture. Two sets of parametric analysis are run characterizing the clay–cement either with a linear elastic-perfectly plastic model or with the bonded elasto-plastic model. The same values of unconfined compressions strength (UCS) are specified for the two models to make comparisons meaningful. Results from both series of analysis are compared highlighting the differences in predicted behaviour of the retaining wall and the excavation stability.

  • 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
    Presentation's date: 2012-11
    Presentation of work at congresses

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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.

  • Cimentación directa para eólica marina

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

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  • 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
    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.

  • 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
    Presentation's date: 2012
    Presentation of work at congresses

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  • 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
    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.

  • 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
    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, Amadeu
    International Conference Offshore Site Investigation and Geotechnics
    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.

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

     Eramo, N.; Modoni, Giuseppe; Arroyo Alvarez de Toledo, Marcos
    International Symposium TC28
    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.

  • 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
    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
    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.

  • Analysis of tunnel excavation in London Clay incorporating soil structure

     González, Nubia A.; Rouainia, Mohamed; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    Géotechnique
    Date of publication: 2012-08
    Journal article

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  • GEOHAZARDS AND GEOMECHANICS

     Arroyo Alvarez de Toledo, Marcos
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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
    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.

  • 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
    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.

  • 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
    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
    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
    Presentation's date: 2011
    Presentation of work at congresses

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  • Design of jet-grouting for tunnel waterproofing

     Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio; Croce, Paolo; Modoni, Giuseppe
    International Symposium TC28
    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.

  • Evaluation of self-combustion risk in tire derived aggregate fills

     Arroyo Alvarez de Toledo, Marcos; San Martin, Ignacio; Olivella Pastalle, Sebastian; Saaltink, Maarten Willem
    Waste management
    Date of publication: 2011-09
    Journal article

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    Lightweight tire derived aggregate (TDA) fills are a proven recycling outlet for waste tires, requiring relatively low cost waste processing and being competitively priced against other lightweight fill alternatives. However its value has been marred as several TDA fills have self-combusted during the early applications of this technique. An empirical review of these cases led to prescriptive guidelines from the ASTM aimed at avoiding this problem. This approach has been successful in avoiding further incidents of self-combustion. However, at present there remains no rational method available to quantify selfcombustion risk in TDA fills. This means that it is not clear which aspects of the ASTM guidelines are essential and which are accessory. This hinders the practical use of TDA fills despite their inherent advantages as lightweight fill. Here a quantitative approach to self-combustion risk evaluation is developed and illustrated with a parametric analysis of an embankment case. This is later particularized to model a reported field self-combustion case. The approach is based on the available experimental observations and incorporates well-tested methodological (ISO corrosion evaluation) and theoretical tools (finite element analysis of coupled heat and mass flow). The results obtained offer clear insights into the critical aspects of the problem, allowing already some meaningful recommendations for guideline revision.

  • Compression and shear wave propagation in cemented sand specimens

     Amaral, Miguel F.; Viana da Fonseca, A.; Arroyo Alvarez de Toledo, Marcos; Cascante, G.; Carvalho, J.
    Géotechnique Letters
    Date of publication: 2011
    Journal article

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    Ultrasonic and bender element tests in the laboratory are typically used to measure elastic modulus and damping ratio. However, interpretation of the results is challenging for a variety of reasons, including the influence of experimental details, geometrical effects and the analytical techniques used for data processing. It is therefore convenient to cross-check results by performing several independent measurements. Three different types of measurements were performed on cementedsand specimens. Longitudinal waves or constrained compressional waves in a cylindrical specimen were generated in a high-frequency range (20–70 kHz) using a newly designed transducer interface. Full dynamic characterisation was made possible by independent measurement of the transducer response. Pure unconstrained compressional waves or simply compression waves were measured in the same specimens with high-frequency transducers. The shear modulus was computed and used to predict the arrival of shear waves on independent bender element measurements. The predicted arrival was close to first-break estimates, and bender measurements were therefore confidently employed to track cement curing effects on a different set of specimens. The specimen frequency response function obtained from the longitudinal wave measurements was examined in detail and damping ratios were estimated for the compression vibration modes in a rod.

  • Development of a family of constitutive models for Geotechnical Applications

     González Molano, Nubia Aurora
    Defense's date: 2011-11-04
    Department of Geotechnical Engineering and Geo-Sciences, Universitat Politècnica de Catalunya
    Theses

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  • Small strain stiffness and residual strength behaviour of Boom clay: A micro-structural insight

     Merchán Jaimes , Vladimir E.
    Defense's date: 2011-05-20
    Department of Geotechnical Engineering and Geo-Sciences, Universitat Politècnica de Catalunya
    Theses

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  • Cone penetration tests in a virtual calibration chamber

     Arroyo Alvarez de Toledo, Marcos; Butlanska, Joanna; Gens Sole, Antonio; Calvetti, Francesco; Jamiolkowski, Michael
    Géotechnique
    Date of publication: 2011
    Journal article

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    A virtual calibration chamber was built using a threedimensional model based on the discrete-element method. The chamber was then filled with a scaled granular equivalent of Ticino sand, the material properties of which were selected by curve-fitting triaxial tests. Cone penetration tests were then performed under different initial densities and isotropic stresses. Penetration resistance in the virtual calibration chamber was affected by the same cone/chamber size effect that affects physical calibration chambers and was corrected accordingly. The corrected cone resistance obtained from the virtual calibration chamber cone penetration tests shows good quantitative agreement with correlations that summarise previous physical results.

  • 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
    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.

  • 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
    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.

  • Virtual Calibration Chamber CPT on Ticino sand

     Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    International Symposium on Cone Penetration Testing
    Presentation's date: 2010-05
    Presentation of work at congresses

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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).

  • 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
    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.

  • MUESTREO GEOTECNICO DE ALTA CALIDAD EN SUELOS BLANDOS

     Pineda Jimenez, Jubert Andrés; Arroyo Alvarez de Toledo, Marcos
    Participation in a competitive project

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  • Shear wave measurements using bender elements in argillaceous rocks

     Arroyo Alvarez de Toledo, Marcos; Pineda Jimenez, Jubert Andrés; Romero Morales, Enrique Edgar
    Geotechnical testing journal
    Date of publication: 2010-11
    Journal article

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  • Proyecto de terraplenes mediante ensayos ¿in situ¿: predicción y observaciones

     Arroyo Alvarez de Toledo, Marcos; Mateos, T.; Baró, Laura
    Carreteras (Madrid. 1982)
    Date of publication: 2010
    Journal article

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  • Identification of bonded clay parameters in SBPM tests: a numerical study

     González, N; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    Soils and foundations
    Date of publication: 2009
    Journal article

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  • Access to the full text
    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
    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)

  • 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
    Presentation's date: 2009
    Presentation of work at congresses

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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.

  • 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
    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

  • 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
    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.

  • MODELACION GEOTECNICA AVANZADA DE TRATAMIENTOS DEL TERRENO POR EROSION Y MEZCLA.APLICACION AL JET-GROUTING

     Garitte, Benoit; Vaunat, Jean; Arroyo Alvarez de Toledo, Marcos; Olivella Pastalle, Sebastian; Gens Sole, Antonio
    Participation in a competitive project

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  • La simulación numérica y el ensayo presiométrico

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

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