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  • Deep enclosures versus pumping to reduce settlements during shaft excavations

     Pujades Garnes, Estanislao; Vázquez Suñé, Enric; Carrera Ramírez, Jesús; Vilarrasa Riaño, Victor; De Simone, Silvia; Jurado Elices, Anna; Ledesma Villalba, Alberto; Ramos Schneider, Gonzalo; Lloret Morancho, Antonio
    Engineering geology
    Vol. 169, p. 100-111
    DOI: 10.1016/j.enggeo.2013.11.017
    Date of publication: 2014-02-04
    Journal article

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    Deep excavations in aquifers may be constructed by combining pumping with the cut and cover method. The enclosures are often deepened more than structurally needed, in order to diminish the risk of heave or fluidisation inside the excavation, and to reduce pumping rates and the associated settlements outside jet-grouting piles are sometimes adopted for lengthening. We analysed the water-proofing efficiency of jet-grouting and the need for water isolation in preconsolidated sediments. We used data obtained from two shaft excavations during the construction of the high speed train tunnel in Barcelona, located adjacent to the Sagrada Familia Basilica. Jet-grouting was characterised using pumping tests before and after the construction of the enclosure. The effectiveness of deepened enclosures was evaluated by comparing settlements caused and discharges required for several dewatering scenarios. Differences between them lie in the depth of the enclosures. Settlements were calculated analytically, using the drawdown obtained from a hydrogeological model, and numerically employing a hydro-mechanical model. Results show that jet-grouting reduced the permeability of the soil (90% reduction, from 5.5 to 0.6 m/d). However, this reduction only affected the pile area, so that the necessary pumping rate and the settlements outside the enclosure were only reduced by 40%. Results also show that settlements due to groundwater pumping are fairly smooth (i.e., differential settlements are small) with low absolute values. Moreover, they recover when pumping ceases. This rather elastic and stiff behaviour reflects the preconsolidated nature of the sediments in Barcelona and the fact that drawdowns concentrate at depth, where the soil is most compact, causing little change in effective stress near the soil surface. Under these conditions, pumping does not pose a serious risk to settlements, and excavation costs can be lowered by constructing the enclosure at the minimum depth required structurally. Also, an intense control of the pumping process may help reducing the conventional safety factors against heave.

    Deep excavations in aquifers may be constructed by combining pumping with the cut and cover method. The enclosures are often deepened more than structurally needed, in order to diminish the risk of heave or fluidisation inside the excavation, and to reduce pumping rates and the associated settlements outside jet-grouting piles are sometimes adopted for lengthening. We analysed the water-proofing efficiency of jet-grouting and the need for water isolation in preconsolidated sediments. We used data obtained from two shaft excavations during the construction of the high speed train tunnel in Barcelona, located adjacent to the Sagrada Familia Basilica. Jet-grouting was characterised using pumping tests before and after the construction of the enclosure. The effectiveness of deepened enclosures was evaluated by comparing settlements caused and discharges required for several dewatering scenarios. Differences between them lie in the depth of the enclosures. Settlements were calculated analytically, using the drawdown obtained from a hydrogeological model, and numerically employing a hydro-mechanical model. Results show that jet-grouting reduced the permeability of the soil (90% reduction, from 5.5 to 0.6 m/d). However, this reduction only affected the pile area, so that the necessary pumping rate and the settlements outside the enclosure were only reduced by 40%. Results also show that settlements due to groundwater pumping are fairly smooth (i.e., differential settlements are small) with low absolute values. Moreover, they recover when pumping ceases. This rather elastic and stiff behaviour reflects the preconsolidated nature of the sediments in Barcelona and the fact that drawdowns concentrate at depth, where the soil is most compact, causing little change in effective stress near the soil surface. Under these conditions, pumping does not pose a serious risk to settlements, and excavation costs can be lowered by constructing the enclosure at the minimum depth required structurally. Also, an intense control of the pumping process may help reducing the conventional safety factors against heave.

  • INTERACCION SUELO-ATMOSFERA: IMPLICACIONES EN EL AGRIETAMIENTO DE SUELOS

     Ledesma Villalba, Alberto; Cuadrado Cabello, Agustin; Cordero Arias, Josbel Andreina; Prat Catalan, Pere
    Competitive project

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  • Ground penetrating radar system for detection of desiccation cracks in soils

     Prat Catalan, Pere; Ledesma Villalba, Alberto; Cuadrado Cabello, Agustin; Levatti, Hector Ulises
    International Symposium on Computational Geomechanics
    p. 249-258
    Presentation's date: 2013-08-22
    Presentation of work at congresses

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    In this paper we explore a relatively simple, non-destructive, indirect technique using a ground penetrating radar (GPR) system to detect cracks that form and propagate inside a soil specimen during desiccation. Although GPR devices have been used for multiple applications, their use in the detection of small cracks (few millimeters wide), has not been demonstrated yet. The experiments and the methodology used to test the accuracy of a small commercial GPR device for crack identification are described. The main objective was to identify what type of signals and what crack width can be detected using the GPR device. The results indicate that cracks of one or two millimeters wide can be detected depending on its position and shape. On the other hand, sub-millimeter cracks are undetectable with the currently existing devices in the market. In spite of the limitations the GPR method can be useful to find time-related bounds of when the cracks appear, and to point at their location. Because the GPR systems are in constant evolution this technique could become a very versatile and convenient method to scan soils under different kinds of processes both in the laboratory and in the field.

  • Evidences of hierarchy in cracking of drying soils

     Lakshmikantha, Ramasesha Mookanahallipatna; Prat Catalan, Pere; Ledesma Villalba, Alberto
    Geo-Congress
    p. 782-789
    DOI: 10.1061/9780784412787.078
    Presentation's date: 2013-03
    Presentation of work at congresses

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    A large variety of morphologies of crack patterns can be found in nature. In many cases the cracks or joints form a closed network and thus divide a two-dimensional surface into distinct domains. Hierarchical patterns are natural phenomena in drying soils where they form and evolve driven by changes in material strength due to natural heterogeneities or due to cycles of stress increase and decrease following seasonal environmental changes. The process of division of domains usually follows a pattern that suggests the existence of some hierarchy. The hierarchical nature can be explained by three important processes: (1) stress generation beyond the material strength; (2) direction of stress generation; and (3) stress redistribution in the vicinity or inside the newly formed domain. In order to substantiate the theory of hierarchical crack pattern formation, experimental evidences showing the existence of hierarchy during crack pattern formation in laboratory desiccation tests is presented and analyzed.

  • Soil characterization and compressibility parameters of Bogota clay due to suction changes

     Ávila1, G.E.; Ledesma Villalba, Alberto; Lloret Morancho, Antonio
    Pan-American Conference on Unsaturated Soils
    p. 285-290
    Presentation's date: 2013-02
    Presentation of work at congresses

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    Parameters such as soil fabric, mineral composition, plasticity and grain size distribution together with soil-volume behavior are essential for the evaluation of shrinkage and cracking processes in soils. This paper presents the results of a laboratory testing program conducted on surface Bogota´ clay to evaluate basic geotechnical properties and compressibility soil parameters due to suction changes. Water retention curves and suction controlled oedometer tests, were used to evaluate the effects of suction changes. Calibration of suction imposed with Polyethylene Glycol of 35000 g/mol (PEG 35000) is presented here because it was only available for PEG 20000 and of lower molecular mass. Results show that the air entry value of the Bogota´ clay is high, that there is an important hysteretic behavior of the clay during drying and wetting cycles and that suction cycles produce a significant increase in the preconsolidation stress and in the stiffness parameters of the soil

  • One-dimensional cracking model in clayey soils

     Ávila1, G.E.; Ledesma Villalba, Alberto; Lloret Morancho, Antonio
    International Conference on Soil Mechanics and Geotechnical Engineering
    p. 1077-1080
    Presentation's date: 2013-09-04
    Presentation of work at congresses

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    It is difficult to formulate a general model to capture cracking initiation and evolution, because there are multiple factors that influence these processes. In order to simplify the evaluation and get more insight on the phenomenon, a series of shrinkage tests were performed inducing one-dimensional primary cracking on remolded clay from Bogotá. The results allowed the proposal of a conceptual model that, based on mould shape factor, initial moisture content and evaporation rate, may predict time for crack initiation and identify the location and direction of primary and secondary cracks. Results indicate that boundary conditions play a significant role in cracking evolution, due to the restrictions imposed to the free shrinkage and to the homogeneous evaporation rate. The moulds used for soil desiccation, allowed the induction of predefined cracks when their shape factor values were greater than 1.5. In these cases the model is simple and may be considered as a model of cracking with one degree of freedom. When moulds have a shape factor between 1 and 1.5, the degrees of freedom increase dramatically leading to much more complex crack patterns.

    It is difficult to formulate a general model to capture cracking initiation and evolution, because there are multiple factors that influence these processes. In order to simplify the evaluation and get more insight on the phenomenon, a series of shrinkage tests were performed inducing one-dimensional primary cracking on remolded clay from Bogotá. The results allowed the proposal of a conceptual model that, based on mould shape factor, initial moisture content and evaporation rate, may predict time for crack initiation and identify the location and direction of primary and secondary cracks. Results indicate that boundary conditions play a significant role in cracking evolution, due to the restrictions imposed to the free shrinkage and to the homogeneous evaporation rate. The moulds used for soil desiccation, allowed the induction of predefined cracks when their shape factor values were greater than 1.5. In these cases the model is simple and may be considered as a model of cracking with one degree of freedom. When moulds have a shape factor between 1 and 1.5, the degrees of freedom increase dramatically leading to much more complex crack patterns.

  • Origin and mechanism of cracks seen at the bottom of a desiccating soil specimen

     Lakshmikantha, Ramasesha Mookanahallipatna; Prat Catalan, Pere; Reig, Ricard; Ledesma Villalba, Alberto
    Geo-Congress
    p. 790-799
    DOI: 10.1061/9780784412787.079
    Presentation's date: 2013-03
    Presentation of work at congresses

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    During a laboratory experimental campaign (related to the PhD thesis of the first author) on soil cracking due to drying, several unseen morphological observations were made. Cracks were observed at the bottom of the desiccating specimen apart from the usual cracks at the drying exposed surface. The cracks observed at the bottom are a particularly interesting pattern of fissures, which is different from the one observed at the top specimen. That complicates the analysis of crack development, and obviously has many consequences on the strength properties of the material. In this paper we present the results of the laboratory experiments carried out especially to explore the origins and mechanisms of propagation of the cracks observed at the bottom of the specimen. Those experiments were conducted with the same specimen size but terminating the test at different stages of drying and observing the presence of cracks at the bottom. The data of different sensors at different locations in the specimen for a number of tests at different drying stages, along with the observation from images taken during the tests, lead to the identification of the mechanism of crack initiation at the bottom.

  • Experimental evidence of size effect in soil cracking

     Lakshmikantha, M. R.; Prat Catalan, Pere; Ledesma Villalba, Alberto
    Canadian geotechnical journal
    Vol. 49, num. 3, p. 264-284
    DOI: 10.1139/t11-102
    Date of publication: 2012-03
    Journal article

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  • Influence of water density on the water-retention curve of expansive clays

     Jacinto, Carlos Abel; Villar, M.V.; Ledesma Villalba, Alberto
    Géotechnique
    Vol. 62, num. 8, p. 657-667
    DOI: 10.1680/geot.7.00127
    Date of publication: 2012-08
    Journal article

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  • Excavación de un pozo profundo para revisión de una tuneladora en el centro de Barcelona

     Ledesma Villalba, Alberto; Lloret Morancho, Antonio; de Santos, C.; Ramos, Gonzalo; Vázquez Suñé, Enric; Alonso Pérez de Agreda, Eduardo; Pujades Garnes, Estanislao; Carrera Ramírez, Jesús
    Simposio Nacional de Ingeniería Geotécnica
    p. 807-817
    Presentation's date: 2012
    Presentation of work at congresses

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  • Effects of the foot evolution on the behaviour of slow-moving landslides

     Ferrari, A.; Ledesma Villalba, Alberto; Gonzalez, D. A; Corominas Dulcet, Jordi
    Engineering geology
    Vol. 117, num. 3-4, p. 217-228
    DOI: 10.1016/j.enggeo.2010.11.001
    Date of publication: 2011-02
    Journal article

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    Análisis numérico de los esfuerzos verticales en el paramento de un muro de tierra reforzada en suelo diabásico  Open access

     Puig Damians, Ivan; Josa Garcia-tornel, Alejandro; Albuquerque, P.J.R.; Lloret Morancho, Antonio; Ledesma Villalba, Alberto; de Santos, C.
    Pan-Am CGS Geotechnical Conference. Pan-American Conference on Soil Mechanics and Geotechnical Engineering. Canadian Geotechnical Conference. Pan-American Conference on Teaching and Learning of Geotechnical Engineering
    p. 1-9
    Presentation's date: 2011-10-03
    Presentation of work at congresses

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    The paper presents a numerical analysis of the service behaviour of a reinforced soil wall constructed in a diabasic soil. A 2D model developed through the Finite Element Method (FEM) using the commercial computer software PLAXIS has been developed for this purpose. This model has been applied to the case of a 6 meters high wall constructed on a diabasic, lateritic and porous underlying soil, common to the region of Campinas (São Paulo, Brazil). The geotechnical properties of this soil have been quantified for different compaction levels. In particular the vertical stresses in the front structure of the wall have been analyzed. The results show that variations in the soil stiffness and of the structure elements geometry cause significant variations of the stress-strain state and the forces that are generated. Mediante el desarrollo de un modelo numérico 2D por el método de los elementos finitos (M.E.F.) con el programa comercial de ordenador PLAXIS se ha modelado el comportamiento en servicio de muros de tierra reforzada. Este modelo se ha aplicado al caso de un muro de 6 metros de altura ejecutado en suelo del diabásico, laterítico y poroso, común en la región de Campinas (São Paulo, Brasil), con propiedades resistentes variables que se han cuantificado según diferentes niveles de compactación. Utilizando este modelo se ha estudiado, en particular, el estado tensional en el paramento del muro. Los resultados más relevantes de dicho análisis, presentados en este documento, muestran que variaciones tanto en la rigidez del terreno como en la geometría de los elementos constructivos provocan cambios significativos en el estado tenso-deformacional y en de los esfuerzos que se generan.

  • Backanalysis of measured movements in ageing tunnels

     de Santos, C.; Ledesma Villalba, Alberto; Gens Sole, Antonio
    International Symposium TC28
    p. 223-230
    Presentation's date: 2011-05
    Presentation of work at congresses

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    The paper describes a procedure to perform backanalysis in a systematic manner in the context of ageing tunnels. Basically the input data include information on relative displacements or deformations of specific points in the lining of a tunnel exhibiting long term movements and the objective of the procedure is to identify a set of parameters that characterize the surrounding soil and the lining properties. Any damage in the infrastructure should give a change in those parameters identified. The analysis should be able to obtain useful information for the manager of the tunnel, in terms of maintenance, repair of some sections, warning in case of danger, etc. The paper presents the basic theory of parameter identification and an application to the backanalysis of a tunnel section from London Underground, where some measurements of rotation of lining segments are available.

  • Evaluation of alternative methodologies to minimize movements of a diaphragm wall close to buildings

     de Santos, C.; Ledesma Villalba, Alberto; Lloret Morancho, Antonio; Alonso Pérez de Agreda, Eduardo
    European Conference on Soil Mechanics and Geotechnical Engineering
    p. 1461-1466
    Presentation's date: 2011-09-13
    Presentation of work at congresses

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    In the framework of the construction of the high-speed railway passing through Barcelona, a large excavation (21m depth) has made to about 2 m of a building. The excavation was done in the quaternary material typical of the Barcelona plain which consists mainly of low plasticity and slightly cemented compact clays. This material due to its high stiffness can be considered as a "hard soil". In order to minimize movements, several methodologies were considered: change in the thickness of the diaphragm walls, increasing the length of the diaphragm walls and location of struts. The predictions of movements were performed using PLAXIS code, considering model parameters estimated from pressuremeter tests and resonant column. The smallest displacements were obtained if struts were placed in advance just below the maximum excavation level. Those struts had only 3 m thickness below the maximum excavation depth, and were built every 5.5 m in horizontal direction. The measured movements were somewhat lower than expected and the building suffered no damage. The paper demonstrates that struts below the maximum excavation level constitute a safe design when movements induced to buildings are a major concern.

  • Micro-measurement and monitoring system for ageing underground infrastructure (UndergroundM3)

     Soga, K.; Ledesma Villalba, Alberto; Roncaglia, A.; Vanícek, I.
    International Symposium TC28
    p. 197-204
    Presentation's date: 2011-05
    Presentation of work at congresses

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    Advances in the development of computer vision, miniature micro-electro-mechanical systems (MEMS) and wireless sensor network (WSN) offer intriguing possibilities that can radically alter the paradigms underlying existing methods of condition assessment and monitoring of ageing civil engineering infrastructure. This paper describes some of the outcomes of the European Science Foundation project “Micro-Measurement and Monitoring System for Ageing Underground Infrastructures (Underground M3)”. The main aim of the project was to develop a system that uses a tiered approach to monitor the degree and rate of tunnel deterioration. The system comprises of (1) Tier 1: Micro-detection using advances in computer vision and (2) Tier 2: Micro-monitoring and communication using advances in MEMS and WSN. These potentially lowcost technologies will be able to reduce costs associated with end-of-life structures, which is essential to the viability of rehabilitation, repair and reuse. The paper describes the actual deployment and testing of these innovative monitoring tools in tunnels of London Underground, Prague Metro and Barcelona Metro.

  • FISURACION TRIDIMENSIONAL EN SUELOS DEBIDA A OSCILACIONES DE VARIABLES MEDIOAMBIENTALES

     Ledesma Villalba, Alberto; Jacinto, Carlos Abel; Levatti, Hector Ulises; Prat Catalan, Pere
    Competitive project

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  • Thermo-Hydro-Mechanical Behaviour of expansive clays under high temperatures  Open access

     CARLOS JACINTO, ABEL
    Department of Geotechnical Engineering and Geo-Sciences, Universitat Politècnica de Catalunya
    Theses

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    Esta Tesis presenta los resultados de la investigación desarrollada en el marco del proyecto Temperature Buffer Test (TBT). El objetivo general de este proyecto es investigar el desempeño de la bentonita usada en barreras de ingeniería bajo la acción de las altas temperaturas que se esperan alrededor de los contenedores con residuos vitrificados. Dentro del proyecto, se ha implementado un ensayo de campo a escala real que simula el almacenamiento de residuos radioactivos de alta actividad. Adicionalmente, se realizaron experimentos en laboratorio para evaluar la respuesta de la bentonita usada en el proyecto bajo diferentes acciones externas.Las formulaciones que se usan para analizar el comportamiento de barreras de ingeniería de arcillas se escriben en términos de las variables de estado usando relaciones constitutivas. Entre esas leyes la curva de retención define la relación constitutiva entre la cantidad de agua en el suelo y su nivel de energía. Tradicionalmente, la influencia de variables externas como la temperatura y la fábrica del suelo sobre la capacidad de retención de agua del suelo se analiza utilizando conceptos derivados del modelo capilar. Sin embargo, estos análisis sistemáticamente fallaron para explicar las observaciones experimentales. En esta Tesis, se han evaluado los datos experimentales obtenidos en muestras de bentonita ensayadas a diferentes temperaturas y densidades usando una aproximación derivada a partir de conceptos de termodinámica de adsorción. Esta aproximación también define una herramienta para introducir en una manera simple el efecto de temperatura y densidad de la muestra en las simulaciones numéricas.En general se supone que la interacción entre la esmectita, que es el principal mineral de la bentonita, y el agua cambia las propiedades del agua retenida en el suelo. En particular, experimentos a nivel mineralógico así como los datos obtenidos en muestras compactadas de arcilla expansiva sugieren valores de la densidad del agua mayores que 1.0 Mg/m3 (es decir, la densidad del agua libre). Desde un punto de vista práctico, este efecto se traduce en valores calculados del grado de saturación mayor que uno para valores bajos de succión. Este aspecto es importante cuando se realizan análisis numéricos, debido a que las ecuaciones de balance se basan en el grado de saturación como la principal variable para indicar el contenido de agua en el medio poroso. En esta Tesis se ha desarrollado una metodología que define la densidad del agua como una función de la energía del agua en los poros del suelo. Este método fue usado para analizar datos publicados de la capacidad de retención de agua de muestras compactadas de diferentes bentonitas.El análisis de la respuesta mecánica de arcillas expansivas bajo acciones externas como aquellas típicamente encontradas en barreras de ingeniería es una tarea compleja. Los modelos constitutivos usados en los cálculos numéricos deben ser capaces de simular los principales aspectos de la respuesta material. En esta Tesis se han adoptado modelos previamente desarrollados para simular el comportamiento de muestras compactadas de arcilla expansiva. Los parámetros de estos modelos se calibraron usando datos experimentales que corresponden a muestras compactadas de bentonita MX-80, el material adoptado como referencia en el proyecto TBT.Los conceptos desarrollados en esta Tesis se incorporaron en un código numérico capaz de resolver problemas acoplados en medios porosos deformables. Este código fue aplicado tanto para el análisis de un ensayo de maqueta como para la simulación del ensayo in situ, ambos desarrollados en el marco del proyecto TBT. Las simulaciones numéricas demostraron las capacidades del código para capturar la tendencia general de los datos experimentales. Además, el análisis de los resultados numéricos puso de manifiesto los diferentes fenómenos que tienen lugar en los procesos acoplados así como los mecanismos de interacción entre ellos.

    This Thesis presents the results of the research carried out in the framework of the Temperature Buffer Test (TBT) project. The overall objective of this project is to investigate how well the bentonite used in engineered barriers can endure the high temperatures expected to be found around vitrified waste canisters. Within the project, a full-scale field test that simulates the deposition of high level radioactive waste has been implemented. Additionally, laboratory experiments were carried out to evaluate the response of the bentonite used in the project under different external actions.Coupled formulations used to analyse the behaviour of an engineered clay barrier are written in terms of the state variables by using constitutive relations. Among these laws the soil water retention curve (SWRC) defines the constitutive relationship between the amount of water in the soil and its energy status. Traditionally, the influence of external variables like temperature and soil fabric on the water retention capacity of soils has been analysed using concepts derived from the capillary model. However, theses analyses systematically failed to explain the experimental observations. In this Thesis, experimental data obtained on bentonite samples tested at different temperatures and densities were evaluated using an approach derived from concepts of thermodynamic of adsorption. This approach also gives a tool to introduce in a simple way the effect of temperature and sample porosity in numerical simulations.It is generally accepted that the interaction between smectite, which is the main mineral of bentonite, and water changes the properties of the water retained in the soil. In particular, values of the water density higher than 1.0 Mg/m3 (i.e. the density of the free water) have been suggested by experiments at mineralogical level as well as by data obtained on compacted samples of expansive clays. From a practical point of view this effect traduces in values of degree of saturation higher than one at lower values of suction. This is important when a numerical analysis is being performed, as balance equations are based on the degree of saturation as the main variable to indicate the water content within the porous medium. In this Thesis a methodology that defines the water density as a function of the energy of the water within the soil pores was developed. This method was applied to analyse published data about the water retention capacity for compacted samples of different bentonites.The analysis of the mechanical response of expansive clays under external actions as those typically found in engineered barriers is a complex task. Constitutive models used in numerical calculations have to be able to simulate the main aspects of the material response. Models previously developed to simulate the behaviour of compacted samples made up of expansive clay were adopted in this Thesis. Parameters in these models were calibrated using experimental data corresponding to compacted samples of MX-80 bentonite, the material adopted as reference in the TBT project.Concepts developed in the Thesis were included in a numerical code able to solve coupled problems in deformable porous media. This code was then applied to the analysis of a mock-up experiment and to the simulation of the in situ test carried out within the framework of the TBT project. Theses numerical simulations showed the capabilities of the code to capture the general tendency of the experimental data. Additionally, the analysis of numerical results enhanced the understanding of the different phenomena that take place in coupled processes as well as the interaction mechanisms between them.

  • Image Analysis for the Quantification of a Developing Crack Network on a Drying Soil

     Lakshmikantha, M R; Prat Catalan, Pere; Ledesma Villalba, Alberto
    Geotechnical testing journal
    Vol. 32, num. 6, p. 505-515
    DOI: 10.1520/GTJ102216
    Date of publication: 2009-11
    Journal article

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  • Experimental and theoretical analysis of cracking in drying soils.

     Lakshmikantha, Ramasesha Mookanahallipatna
    Barcelona School of Civil Engineering (ETSECCPB), Universitat Politècnica de Catalunya
    Theses

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  • ROTURA PROGRESIVA Y REACTIVACION DE GRANDES DESLIZAMIENTOS: ANALISIS, PREDICCION Y RIESGOS

     Corominas Dulcet, Jordi; Moya Sanchez, Jose; Baeza Adell, Cristina; Ledesma Villalba, Alberto; Lloret Morancho, Antonio; Olivella Pastalle, Sebastian; Suriol Castellvi, Jose; Alonso Pérez de Agreda, Eduardo
    Competitive project

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  • LIVING WITH LANDSLIDE RISK IN EUROPE:ASSESSMENT, EFFECTS OF GLOBAL CHANGE AND RISK MANAGEMENT STRATEGIES

     Hürlimann Ziegler, Marcel; Olivella Pastalle, Sebastian; Fabregas Canovas, Francisco Javier; Alonso Pérez de Agreda, Eduardo; Moya Sanchez, Jose; Lantada Zarzosa, Nieves; Romero Morales, Enrique Edgar; Aguasca Sole, Alberto; Mallorqui Franquet, Jordi Joan; Baeza Adell, Cristina; Gili Ripoll, Jose Antonio; Ledesma Villalba, Alberto; Lloret Morancho, Antonio; Pinyol Puigmarti, Nuria Merce; Corominas Dulcet, Jordi
    Competitive project

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  • BIA2008-06614 - ROTURA PROGRESIVA Y REACTIVACION DE GRANDES DESLIZAMIENTOS: ANALISIS, PREDICCION Y RIESGOS

     Alonso Pérez de Agreda, Eduardo; Corominas Dulcet, Jordi; Romero Morales, Enrique Edgar; Moya Sanchez, Jose; Baeza Adell, Cristina; Ledesma Villalba, Alberto; Lloret Morancho, Antonio; Olivella Pastalle, Sebastian; Suriol Castellvi, Jose
    Competitive project

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  • Coupled Thermohydromechanical Modeling of the Full-Scale In Situ Test "Prototype Repository

     Chen, Gj; Ledesma Villalba, Alberto
    Journal of geotechnical and geoenvironmental engineering
    Vol. 135, num. 1, p. 121-132
    Date of publication: 2009-01
    Journal article

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  • Adaptation of the van Genuchten expression to the effects of temperature and density for compacted bentonites

     Jacinto, Carlos Abel; Villar, M V; Gomez-Espina, R; Ledesma Villalba, Alberto
    Applied clay science
    Vol. 42, num. 3-4, p. 575-582
    Date of publication: 2009-01
    Journal article

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  • Bentonite THM behaviour at high temperatures: experimental and numerical analysis

     Akesson, M; Jacinto, Carlos Abel; Gatabin, C; Sanchez, M; Ledesma Villalba, Alberto
    Géotechnique
    Vol. 59, num. 4, p. 307-318
    Date of publication: 2009-05
    Journal article

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  • Numerical modelling of desiccation processes in clayey soils

     Levatti, Hector Ulises; Prat Catalan, Pere; Ledesma Villalba, Alberto
    International Symposium on Computational Geomechanics
    p. 630-639
    Presentation's date: 2009-04-30
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  • Access to the full text
    Influence of cracking in the desiccation process of clay soils  Open access

     Levatti, Hector Ulises; Prat Catalan, Pere; Ledesma Villalba, Alberto
    International Conference on Computational Plasticity Fundamentals and Applications
    p. 1-4
    Presentation's date: 2009-09-03
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    It is well known that clayey soils undergoing desiccation tend to shrink and eventually crack. Analysis of the behaviour and influence of cracks in these types of soils is very important in several engineering fields such as mine tailing dams, long-term radioactive waste storage, impervious core of earth dams, and in any situation where clay is used as a barrier to fluid flow. Loss of humidity and cracking changes the permeability of such barriers that may no longer work properly and pose potentially high risks to property and lives. This paper presents an analysis of cracking during drying of soils using a computer code de-veloped within the framework of the finite element and finite differences methods. A study of the influence of crack initiation and propagation in the desiccation process is also undertaken, with a comparative analysis of the phenomenon both with and without crack generation that allows some preliminary conclusions about the desiccation problem. The computer code has been implemented within the MatLab environment. The formulation is based on the principles of the unsaturated soil mechanics and the mechanics of a continuum medium. The partial differential equations that govern the problem are solved using the finite element (Galerkin) method in space and the finite differences method, using the Crank-Nicholson scheme, in time. Further developments of the code will include fracture mechanics principles to simulate crack propagation.

  • Influence of temperature on the water retention capacity of soils analysis using solution thermodynamics

     Jacinto, Abel Carlos; Ledesma Villalba, Alberto; Villar Galicia, María Victoria; Gómez-Espina, Ramón
    International Conference on Unsaturated Soils
    p. 555-560
    Presentation's date: 2009
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  • Desecación y deformación de suelos arcillosos

     Levatti, Hector Ulises; Ledesma Villalba, Alberto; Prat Catalan, Pere
    Congresso de Métodos Numéricos em Engenharia
    p. 355
    Presentation's date: 2009-06-30
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  • Effect of soil saturation changes on pressure on tunnel linings

     de Santos, C.; Ledesma Villalba, Alberto; Lloret Morancho, Antonio
    International Conference on Soil Mechanics and Geotechnical Engineering
    p. 1766-1769
    Presentation's date: 2009-10
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    It is well known that changes in soil degree of saturation have an important influence on mechanical soil properties. Decreasing suction in soil leads to an increase of specific weight and to a decrease of stiffness and strength. These mechanical changes may have an important influence on underground works, particularly on subsurface tunnels. In fact, decreasing soil cohesion due to saturation reduces arching effects above tunnels. Recent developments in unsaturated soil behaviour include numerical models coupling hydromechanical phenomena and considering elastoplastic constitutive laws. However, these techniques are seldom used in practical applications. This paper presents a methodology to compute stress and strain changes in a tunnel lining due to changes in soil saturation, using relatively conventional tools. The motivation of this work comes from a real case in Barcelona, where a Metro tunnel received an increment of loading due to loss of cohesion of upper layers after irrigation. The Finite Element programme “PLAXIS” was used. The paper concludes that the effect of soil saturation changes on underground structures can be assessed by using conventional Finite Element codes, if the variation of stiffness and strength with suction is previously known. The analyses presented in the paper show that changes in density and stiffness due to saturation have little influence on the stresses in the sidewalls of a subsurface tunnel. However, reduction of cohesion due to suction changes may reduce arching effects above the tunnel and would generate high stresses in the tunnel lining.

  • Numerical modelling of desiccation proccesses in clayey soils

     Levatti, Hector Ulises; Prat Catalan, Pere; Ledesma Villalba, Alberto
    International Symposium on Computational Geomechanics
    p. 630-639
    Presentation's date: 2009-05-30
    Presentation of work at congresses

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  • Effect of Moisture Content on Tensile Strength and Fracture Toughness of a Silty Soil

     Lakshmikantha, M R; Prat Catalan, Pere; Tapia, J; Ledesma Villalba, Alberto
    Europ. Conf. on Unsaturated Soils E-UNSAT
    p. 1
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  • Sécheresse et constructions

     Ledesma Villalba, Alberto; Prat Catalan, Pere
    Symposium international "Sécheresse et constructions"
    p. 163-168
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  • The viscous component in slow moving landslides. A practical case

     González, D A; Ledesma Villalba, Alberto; Corominas Dulcet, Jordi
    10th Intl. Symp. on Landslides and Engineered Slopes
    p. 237-242
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  • Fracture mechanics for crack propagation in drying soils

     Prat Catalan, Pere; Ledesma Villalba, Alberto; Lakshmikantha, M. R.; Levatti, Hector Ulises; Tapia, J.
    International Conference of International Association for Computer Methods and Advances in Geomechanics
    p. 1060-1067
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  • Analysis of measured movements in ageing tunnels

     Santos, C de; Ledesma Villalba, Alberto; Gens Sole, Antonio
    II European Conference of International Conference for Engineerigng Geology
    p. 121-126
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  • Using ICT in Geo-Engineering education: the case of UPC at Barcelona, Spain

     Ledesma Villalba, Alberto; Prat Catalan, Pere
    First Int. Conf. on Education and Training in Geo-Engineering Sciences
    p. 1
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  • Effect of moisture content on tensile strength and fracture toughness of a silty soil

     Prat Catalan, Pere; Ledesma Villalba, Alberto
    First European Conference on Unsaturated Soild
    p. 405-409
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  • Diseño y ejecución de un muro pantalla pretensado y con contrafuertes

     Molins Borrell, Climent; Ledesma Villalba, Alberto; Rafael, Casals; Jaen Gonzalez, Carlos
    Hormigon y acero
    Vol. 57, num. 247, p. 45-54
    Date of publication: 2008-03
    Journal article

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  • Discussion on "Experimental study on fracture toughness and tensile strength of a clay"

     Prat Catalan, Pere; Ledesma Villalba, Alberto; Lakshmikantha, M R
    Engineering geology
    Vol. 101, num. 3-4, p. 295-296
    Date of publication: 2008-10
    Journal article

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  • Chemohydromechanical coupled consoldiation for a poroelastic clay buffer in a radioactive waste repository

     Chen, Guangjing; Ledesma Villalba, Alberto
    Transport in porous media
    Vol. 69, num. 2, p. 189-213
    Date of publication: 2007-09
    Journal article

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  • Análisis comparativo del fenómeno de licuación en arenas. Aplicación a Tumaco (Colombia) .  awarded activity

     Garcia Nuñez, Jesus Rafael
    Department of Geotechnical Engineering and Geo-Sciences, Universitat Politècnica de Catalunya
    Theses

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  • THM analysis of a "mock up" laboratory experiment using a double-structure expansive model

     Jacinto, A; Sánchez, Marcelo; Ledesma Villalba, Alberto
    Clays in Natural & Engineered Barriers for Radioactive Waste Disposal. 3rd Int. Meeting
    p. 623-624
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  • Volume change of sand caused by cyclic small shear strains

     Marín Suárez, Carlos; Olivella Pastalle, Sebastian; Lloret Morancho, Antonio; Ledesma Villalba, Alberto; Molins Borrell, Climent
    XIV European Conference on Soil Mechanics and Geotechnical Engineering
    p. 1927-1931
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  • Temperature Buffer Test. Experimental and model results

     Akesson, M; Jacinto, A; Ledesma Villalba, Alberto; Combarieu, de M
    Clays in Natural & Engineered Barriers for Radioactive Waste Disposal. 3rd Int. Meeting
    p. 51-52
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  • Interaction between a large excavation and nearby tunnels at Las Arenas in Barcelona (Spain)

     Ledesma Villalba, Alberto; Molins Borrell, Climent
    XIV European Conference on Soil Mechanics and Geotechnical Engineering
    p. 1847-1852
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  • The Mountain Risk research project: challenges in risk management

     Gonzalez, D A; Corominas Dulcet, Jordi; Ledesma Villalba, Alberto; Moya, J; Gili Ripoll, Jose Antonio
    European Geosciences Union General Assembly
    p. 6788-6797
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  • Effect of temperature on the retention capacity of compacted bentonite: an experimental and numerical investigation

     Jacinto, A; Gómez-Espina, R; Villar, M; Ledesma Villalba, Alberto
    Clays in Natural & Engineered Barriers for Radioactive Waste Disposal. 3rd Int. Meeting
    p. 363-364
    Presentation of work at congresses

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