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Los materiales de refuerzo de bandas de poliéster (PET) se utilizan actualmente de forma rutinaria como refuerzo del suelo para los estructuras de contención de suelo reforzado. Es de esperar que la resistencia y la rigidez de las fibras de poliéster disminuya con el aumento de la temperatura y en presencia de humedad. Esto tiene implicaciones prácticas para la selección del factor parcial de degradación química que se utiliza en el diseño del estado límite de estabili-dad interna en los muros TEM. Este estudio presenta los resultados de los análisis realizados mediante simulaciones numéricas para estimar, en primer lugar, los cambios de temperatura y humedad relativa en el suelo para diferentes propiedades del terreno y condiciones atmosféricas de contorno, y, en segundo lugar, los cambios temporales de resistencia y rigidez en correas de PET enterradas simuladas y colocadas en diferentes entornos de suelo mientras se someten a diferentes cargas de tracción y temperaturas.

The paper presents the work carried out to assess and simulate numerically the phenomenology behind the response of large diameter intermediate-level long-lived nuclear waste (ILW-LL) storage galleries and the corresponding sealing structures. Large scale models were created for this purpose, using advanced constitutive models, accounting for complex coupled phenomena, and representing geometric details at decimeter scale. These challenging simulations provided qualitative and quantitative results on key questions related to the design of this kind of structures, such as the extension of the damaged zone around the gallery, the impact of the thermal load on the water pressure variation around the excavation and on the surrounding geological layers, the duration of the natural hydration phase and the swelling pressure development of the sealing core, and the seals system global stability.

A gas injection test performed on compact bentonite was carried out at the British Geological Survey. The test is composed of two stages (i.e. hydration followed by gas injection). After gas breakthrough and a period of gas flow through the sample, the injection pump was stopped whilst stresses and pore pressures were continuously monitored. A 3D numerical model has been developed to simulate the gas injection test and to achieve similar gas pressure responses. After sensitivity analysis of the model, a satisfactory calibration ap-proach was possible using both hydraulic and coupled hydro-gas-mechanical model assumptions.

Las expansiones ocurridas en el túnel de Lilla son el resultado del crecimiento de cristales de yeso en discontinuidades. Se describe un procedimiento de análisis numérico para el diseño de un túnel en roca anhidrítica expansiva. El modelo incorpora un acoplamiento hidro-mecánico y el transporte de sales disueltas en el agua intersticial e incluye el daño generado en la roca tras la excavación del túnel, la precipitación de cristales en discontinuidades y la dependencia entre las deformaciones de hinchamiento y la masa precipitada de yeso. La respuesta del modelo es coherente con las medidas de campo disponibles.

This document presents preliminary results of FEM-numerical analysis of soil-reinforcement pullout tests. The numerical model has been developed with CODE_BRIGHT and assuming the interfaces as continuum materials. The results of the preliminary parametric analyses described herein provide useful information on the shear behavior modeling of soil-reinforcement strip interfaces under working stress conditions.

This document presents the analysis with CODE_BRIGHT finite element program of a geotechnical case. The problem analyzed is related to a mechanical analysis of soilstructure interaction considering different alternatives for the foundation of a bridge in El Prat de Llobregat (Highway A-2). The comparison of displacements shows that an alternative solution using shallow foundations can be considered in addition to the originally proposed, composed by sheet walls.

Lechago dam (Teruel, Spain) is a 40 m high zoned earth and rockfill dam founded on soft continental deltaic deposits. A relatively narrow central clay core is stabilized by wide rockfill shoulders. The dam was completed in January 2009 and impounding will probably start at the beginning of 2011. The dam was well instrumented and continuous records of stress development, pore water pressures and horizontal and vertical displacements are available for the construction period. The clay core material was investigated by means of tests performed on compacted specimens of Tertiary clays. Rockfill samples were excavated in outcrops of highly fractured Cambrian quartzitic shale. In the years to follow the dam design, an extensive testing program on compacted rockfill gravels was conducted under Relative Humidity control in large diameter oedometer and triaxial cells. The results of this research have been reported in a number of papers. A coupled FE model has been developed to analyze the dam behaviour during construction. Model predictions, essentially based on laboratory tests, are compared with measurements during construction.

3rd Workshop of CODE-BRIGHT Users. 2011, Barcelona., Anthropogenic CO2 emissions are expected to continue to increase worldwide in the next decades. This could dramatically increase CO2 concentrations in the atmosphere. One potential mitigation action is CO2 permanent storage in deep saline aquifers. CO2 is injected as a supercritical fluid (temperature and pressure higher than 31.1 ºC and 7.38 MPa, respectively) so as to obtain a relatively high density that minimizes the volume occupied by this greenhouse gas. CO2 density is highly dependent on temperature and pressure because of its high compressibility (Vilarrasa et al., 2010a), adopting a wide range of values (450-800 kg/m3). Since CO2 is lighter than brine, flow is affected by buoyancy. Buoyancy produces an upslope migration of the CO2 bubble in sloping aquifers. The post-injection fate of CO2 in sloping aquifers has been investigated (e.g. Hesse et al., 2008; Elenius et al., 2010) but without considering the actual shape of the CO2 bubble at the end of injection. However, the shape of the CO2 bubble at the end of injection affects its posterior evolution (McMinn & Juanes, 2009). Gasda et al. (2008) studied the effect of a slope up to 1º during the injection period using a 2D model, which represents injection through a horizontal well. However, CO2 injection through a vertical well, which implies a 3D geometry, has not yet been investigated.CO2 will be injected in the Hontomín CO2 pilot storage site, Burgos (Spain). Hontomín is the site for the CO2 storage Technology Demonstration Plant (TDP) of the Compostilla OXYCFB300 project, operated by Energy City Foundation (CIUDEN). CO2 will be injected through a vertical well in a flank of a dome-like structure with a slope close to 20º at a depth around 1450 m. CO2 injection tests are aimed to gain knowledge on trapping mechanisms and CO2 bubble and pressure evolution. Pressure evolution is important for assessing the caprock integrity and to avoid the open up of preferential paths for CO2 leakage (Vilarrasa et al., 2010b, 2011). These processes are relatively well known in horizontal aquifers, but a high uncertainty still exists in sloping aquifers., V.V. wishes to acknowledge the Spanish Ministry of Science and Innovation (MCI), through the “Formación de Profesorado Universitario”, and the “Colegio de Ingenieros de Caminos, Canales y Puertos – Catalunya” for their financial support. Additionally, we would like to acknowledge the Spanish Government (Ministry of Industry, Tourism and Trade) through the CUIDEN foundation (project ALM/09/18; www.ciuden.es) and the ‘MUSTANG’ project (from the European Community’s Seventh Framework Programme FP7/2007-2013 under grant agreement nº227286 ; www.co2mustang.eu) for their financial support.

7 pages, 5 figures.-- Comunicación presentada en las Novenas Jornadas de Investigación de la Zona No Saturada del Suelo, Barcelona (Spain), 18-20 Noviembre, 2009., [EN] Soil salinzation is a global problem. Salinization is generally caused by salts transported to the soil surface by capillary rising water. Despite its global importance, actual salinization mechanisms are poorly understood (Kampf et al., 2005). We use laboratory experiments and numerical models to show that salt precipitates at the evaporation front, which occurs within a very narrow band. Part of the evaporating water diffuses downwards, where it condensates. This implies that, contrary to widely spread belief, salinization (Xu & Shao, 2002) (i.e. salt precipitation) does not occur below the evaporation front. Instead, the upflowing solution becomes diluted., [ES] La salinización de suelos es un problema global. Generalmente, la salinización es causada por el transporte de sales hacia la superficie por capilaridad y, a pesar de su importancia global, los mecanismos que la controlan aún no están bien descritos (Kampf et al., 2005). En este trabajo, se han llevado a cabo experimentos de laboratorio y simulaciones numéricas que muestran que las sales precipitan en el frente de evaporación, el cual se da en una zona estrecha del suelo y que el flujo de vapor de agua se desplaza, no solo en sentido ascendente, sino también descendente, desde dicho frente de evaporación. El flujo de vapor descendente, condensa, causando la dilución de la solución. Esto implica, que contrariamente a lo creído hasta ahora, la salinización (Xu y Shao, 2002) (la precipitación de sales) no se da por debajo del frente de evaporación., We gratefully acknowledge the financial support received from the EU WATCH project (WATer and global Change) and the Spanish Research Council ATRAPO project.

By employing a combination of ice pressure, liquid pressure and total stress as state variables, a new thermoplastic constitutive model has been developed that encompasses frozen and unfrozen behaviour within a unified effective-stress-based framework. It has been incorporated into a fully coupled thermo-hydro-mechanical (THM) finite element formulation that considers freezing and thawing in water-saturated soils and applied to a large-scale pipeline frost heave test.

Imperial College London is researching with BP some potential impacts of future climate change. BP has a significant number of facilities in cold high-latitude regions, where global climate models predict significant rises in air and ground surface temperature. This could impact on the state and extent of permafrost, potentially posing risks to facilities, infrastructure, and operations (ACIA 2005). The paper reviews the research, focusing on an exemplar study region in eastern Siberia. The key elements included: (1) Developing an approach to provide a best estimate of future climate change. (2) An engineering geological appraisal of the ground conditions in the study region. (3) Performing a parametric study of geothermal conditions in the study region using finite element thermal analyses. (4) Developing a Thermal-Hydraulic-Mechanical modeling approach for assessment of climate change impact on specific engineering facilities. (5) Developing a methodology for incorporating potential climate change considerations into engineering decision-making and design.

Laboratory experiments show that preferential paths develop through saturated impervious clay bodies. A procedure to integrate gas transmission discontinuities into a general THM formulation is described. The technique has been incorporated into a general purpose FE THM code (CODE_BRIGHT) and it has been used to reproduce gas transmission experiments in specimens. The experimentally observed peaks in gas pressure and flow rates, when breakthrough conditions are reached, are reproduced. The paper discusses also the role of local heterogeneity in gas migration. A computational experiment, inspired in the conditions prevailing on the “in situ” large scale GMT test, has been preformed. All the elements of the discretization include an embedded discontinuity. The analysis shows that small variability in buffer properties enhances the development of preferential paths.

Tesis del Departament d'Ingenyeria del Terreny Cartogràfica i Geofísica de la Universitat Politècnica de Catalunya (UPC).-- Fecha de defensa 12.07.1995., [EN] A new formulation for the coupled analysis of thermo- hydro- mechanical problems in saline media is presented. The work ranges from the establishment of the mass, momentum and energy balance equations to its numerical solution by means advanced numerical techniques, including the derivation of some constitutive laws. The resulting computer program (CODE-BRIGHT) can be used to analyze real problems of sealing systems built with porous salt aggregates, which was the original motivation of the work., The balance equations have been formulated taking into account that three main species or components are present in saline media. These are: salt, water and air. One of the peculiarities of saline media with respect to other geological media is that solid phase dissolves at elevated concentrations in the liquid phase which is referred as to brine. Another interesting aspect is the presence of brine inclusions in the solid phase. Dissolution and precipitation of salt leads to a creep strain mechanism. The shape of grains changes by dissolution of salt in zones of stress concentration while recrystallization takes place in zones of lesser stress level. In addition the grains also deform by the ductile behaviour of the crystalline solid. We have derived a new constitutive law for stress- strain behaviour of porous salt aggregates, which is based on coupling an idealized geometry of grains with the basic strain mechanisms., Once the computer code was developed and verified, it has been used to study different phenomena. We present the analysis of porosity variations induced by temperature gradients in unsaturated porous salt aggregates. Temperature differences induce a flux of water vapour counteracted by an opposite brine flux. This flux drags dissolved salt, hence a salt flux towards the hot side takes place. This phenomenon, which may cause strong variations of porosity, has not been studied before. Secondly, the analysis of the behaviour of a brick dam subject to compression in the mine gallery is presented. We show that the hydromechanical coupling is crucial to understand what happens. Initially, there is a brine flux towards the dam because of its large suction. When the pores of the backfill reach saturation, the flux is reversed because convergence of the rock salt cause pore pressure to build up at the dam. A few applications to other problems related to nonsaline media show that the formulation is very versatile., [ES] Presentamos una formulación nueva para el análisis de problemas Termo-hidro-mecánicos en medios salinos. Esta formulación incluye, desde la obtención de ecuaciones de balance de masa, momento y energía hasta su resolución numérica, incluyendo la derivación de algunas ecuaciones constitutivas. El programa de calculo resultante (Code Bright) puede usarse para analizar problemas reales de sistemas de sellado construidos con agregados porosos de sal, que era la motivación original de este trabajo., Las ecuaciones de balance se han formulado teniendo en cuenta que en un medio salino existen tres especies o componentes mayoritarios. Estos son: la sal, el agua y el aire. Uno de los aspectos diferenciadores respecto a otros medios geológicos es que la fase sólida se disuelve a concentraciones elevadas en la fase liquida a la que se llama Salmuera. Otro aspecto interesante es la presencia de inclusiones de salmuera en la fase sólida. La disolución y precipitación de la sal da lugar a un mecanismo de deformación por fluencia. La forma de los granos de sal cambia por disolución en las zonas donde se concentran las tensiones y recristalizacion en las zonas de menor estado tensional. Además los granos también se deforman por el carácter muy dúctil del propio sólido cristalino. Hemos derivado una nueva ley constitutiva tensión deformación para los agregados porosos de sal, que se basa en acoplar una geometría idealizada de los granos con los mecanismos fundamentales de deformación., Una vez que se ha desarrollado y verificado el programa de cálculo, este ha sido aplicado para el estudio de diferentes fenómenos. Presentamos el análisis de las variaciones de porosidad inducidas por gradientes de temperatura en agregados porosos de sal no saturados. Las diferencias de temperatura inducen un flujo de vapor que es contrarrestado por un flujo de salmuera. Este arrastra la sal disuelta y da lugar a un flujo de sal hacia zonas de temperatura más alta.

An appropriate understanding of the interaction and effects of thermal, hydraulic, mechanical and chemical (THMC) phenomena occurring in compacted swelling clay is greatly assisted by the development and use of coupled theoretical formulations. In this contribution one example of such a formulation is presented. Special attention is given to phenomena likely to be encountered in clay barriers and seals used as part of containment systems of nuclear waste. The types of processes considered in the chemical formulation include hydrolysis, complex formation, oxidation/reduction reactions, acid/base reactions, precipitation/dissolution of minerals and cation exchange. Both kinetically controlled and equilibrium-controlled reactions have been incorporated. The coupling between geochemical variables and mechanical behaviour is ensured by a chemomechanical constitutive law that is described in this paper. The formulation has been implemented in a numerical code. An application is presented concerning the performance of a small scale test simulating high-level nuclear waste repository conditions. Also numerical simulations of triaxial and oedometer tests are presentedwhere the samples were subjected to a sequence of mechanical and chemical actions.

"Crampton Price" de la Institution of Civil Engineers (London) Beliche Dam, a zoned earthdam with rockfill shouldersand a central clay core, experienced large collapse settlements due to reservoir impounding and direct action of rainfall. Long-term field records of vertical and horizontal displacements are available as well as a set of largescale laboratory tests on rockfill specimens. It has been the subject of several numerical analyses that failed to capture the relevant effect of weather conditions on the behaviour of the dam. Recent developments in the constitutive modelling of rockfill allow a substantial improvement of modelling capabilities, and this is illustrated in the paper. Laboratory test results under dry and flooded conditions were interpreted, and material parameters were identified. The complete history of dam construction, impoundment and rainfall was then simulated by means of a coupled flow–deformation model. Deformations during construction and impoundment have been reproduced. Long-term deformations have consistently been related to rainfall records. In general, long-term deformations are controlled by the varying wetting history of the dam shoulders and by an intrinsic deformation component. The wetting action comes to an end when the relative humidity of the rockfill reaches 100% for the first time. The paper also discusses scale effects and the role of rockfill permeability in the development of deformations.