http://hdl.handle.net/2117/595 Sun, 19 May 2013 04:46:08 GMT 2013-05-19T04:46:08Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19322 Title: Testing a new submersible drill rig Authors: Romero, F.; Devincenzi, M.J.; Pérez Garcia, N.; Arroyo Alvarez de Toledo, Marcos; Deu, Amadeu Abstract: 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. Thu, 16 May 2013 17:46:05 GMT http://hdl.handle.net/2117/19322 2013-05-16T17:46:05Z Romero, F.; Devincenzi, M.J.; Pérez Garcia, N.; Arroyo Alvarez de Toledo, Marcos; Deu, Amadeu no 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. http://hdl.handle.net/2117/19320 Title: A submersible drill rig for coring soils and rocks Authors: Devincenzi, M.J.; Pérez Garcia, N.; Samoili, K.; Arroyo Alvarez de Toledo, Marcos Abstract: 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. Thu, 16 May 2013 16:33:30 GMT http://hdl.handle.net/2117/19320 2013-05-16T16:33:30Z Devincenzi, M.J.; Pérez Garcia, N.; Samoili, K.; Arroyo Alvarez de Toledo, Marcos no Drill rigs, Geotechnical investigations, Inclination sensors, Injection rates, Nearshores, Operation parameters, Remotely operated submersibles, Renewable Energy industries, Site investigations, Vertical positions 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. http://hdl.handle.net/2117/19319 Title: Design control and monitoring of a jet grouted excavation bottom plug Authors: Eramo, N.; Modoni, Giuseppe; Arroyo Alvarez de Toledo, Marcos Abstract: 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. Thu, 16 May 2013 16:26:07 GMT http://hdl.handle.net/2117/19319 2013-05-16T16:26:07Z Eramo, N.; Modoni, Giuseppe; Arroyo Alvarez de Toledo, Marcos no Adverse effect, Design control, Earth retaining, Execution control, Field trial, Geotechnical conditions, Ground improvement, Injection systems, Injection techniques, Jet grouting, Mechanical response, Statistical design, Surface movement, Surrounding environment, Theoretical models, Urban areas 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. http://hdl.handle.net/2117/19317 Title: SAR measurements of coastal features in the NW Mediterranean Authors: Redondo Apraiz, José Manuel; Martínez Benjamín, Juan José; Díez Rilova, Margarita; Lopez Gonzalez-Nieto, Pilar Thu, 16 May 2013 16:15:04 GMT http://hdl.handle.net/2117/19317 2013-05-16T16:15:04Z Redondo Apraiz, José Manuel; Martínez Benjamín, Juan José; Díez Rilova, Margarita; Lopez Gonzalez-Nieto, Pilar no SAR, Coastal Features, Vortex http://hdl.handle.net/2117/19308 Title: Testing block samples from silty deposits Authors: Pineda Jiménez, Jubert Andrés; Arroyo Alvarez de Toledo, Marcos; Sau Valenzuela, Núria; Gens Solé, Antonio; Pérez, Norma Abstract: 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. Thu, 16 May 2013 13:41:23 GMT http://hdl.handle.net/2117/19308 2013-05-16T13:41:23Z Pineda Jiménez, Jubert Andrés; Arroyo Alvarez de Toledo, Marcos; Sau Valenzuela, Núria; Gens Solé, Antonio; Pérez, Norma no 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. http://hdl.handle.net/2117/19305 Title: Site characterization alternatives for numerical models of a deep excavation Authors: Sau, Núria; Arroyo Alvarez de Toledo, Marcos; Gens Solé, Antonio Abstract: 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. Thu, 16 May 2013 13:29:24 GMT http://hdl.handle.net/2117/19305 2013-05-16T13:29:24Z Sau, Núria; Arroyo Alvarez de Toledo, Marcos; Gens Solé, Antonio no Barcelona, Comparative approach, Crosshole tests, Deep excavation, Excavation sequences, Hardening soil models, Laboratory test, Railway tunnels, Site characterization, Site investigations, Soil characterization 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. http://hdl.handle.net/2117/19303 Title: 3D DEM simulations of CPT in sand Authors: Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Solé, Antonio Abstract: 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. Thu, 16 May 2013 13:18:33 GMT http://hdl.handle.net/2117/19303 2013-05-16T13:18:33Z Butlanska, Joanna; Arroyo Alvarez de Toledo, Marcos; Gens Solé, Antonio no Calibration tests, Cone penetration, Cone penetration tests, DEM Simulation, Different boundary condition, Discrete material, Feasible alternatives, Friction fatigue, High density, Numerical experiments, Numerical results, Particle flow, Point resistance, Reference material, Scaling factors, Shaft resistance, Stationary conditions, Virtual calibration 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. http://hdl.handle.net/2117/19291 Title: Desarrollo de herramientas para la evaluación preliminar de la peligrosidad de corrientes detríticas Authors: Bregoli, Francesco; Bateman Pinzón, Allen; Medina Iglesias, Vicente César de; Hurlimann Ziegler, Marcel Abstract: Con el objetivo de proporcionar recomendaciones para la alerta temprana de fenómenos potencialmente desencadenantes de corrientes detríticas (“Debris Flow”), uno de los temas principales es la identificación preliminar de zonas de riesgo. Esta identificación es sustancialmente diferente de los mapas de riesgo que se suelen realizar por las autoridades de cuenca con el fin de dar una guía para planes de gestión del territorio. En el caso de alerta temprana, una identificación más aproximativa de las zonas de riesgo es suficiente. En esta perspectiva, los dos componentes del riesgo, peligrosidad y vulnerabilidad, se pueden estimar de una manera simplificada. En este trabajo se han desarrollado unas herramientas para la evaluación rápida de peligro por corrientes detríticas. Se han adaptado metodologías existentes y modelos simplificados y se ha llevado a cabo un útil paquete común de metodologías para una rápida evaluación de la peligrosidad. Se modelan tanto la iniciación como la propagación de corrientes detríticas. Uno de los requisitos del proyecto es definir una herramienta utilizable en diferentes contextos donde el nivel de detalle en los datos de entrada puede ser muy variado. Para lograr este objetivo se define un enfoque multinivel. La metodología se aplica en tres cuencas con características diferentes. Thu, 16 May 2013 12:17:48 GMT http://hdl.handle.net/2117/19291 2013-05-16T12:17:48Z Bregoli, Francesco; Bateman Pinzón, Allen; Medina Iglesias, Vicente César de; Hurlimann Ziegler, Marcel no Con el objetivo de proporcionar recomendaciones para la alerta temprana de fenómenos potencialmente desencadenantes de corrientes detríticas (“Debris Flow”), uno de los temas principales es la identificación preliminar de zonas de riesgo. Esta identificación es sustancialmente diferente de los mapas de riesgo que se suelen realizar por las autoridades de cuenca con el fin de dar una guía para planes de gestión del territorio. En el caso de alerta temprana, una identificación más aproximativa de las zonas de riesgo es suficiente. En esta perspectiva, los dos componentes del riesgo, peligrosidad y vulnerabilidad, se pueden estimar de una manera simplificada. En este trabajo se han desarrollado unas herramientas para la evaluación rápida de peligro por corrientes detríticas. Se han adaptado metodologías existentes y modelos simplificados y se ha llevado a cabo un útil paquete común de metodologías para una rápida evaluación de la peligrosidad. Se modelan tanto la iniciación como la propagación de corrientes detríticas. Uno de los requisitos del proyecto es definir una herramienta utilizable en diferentes contextos donde el nivel de detalle en los datos de entrada puede ser muy variado. Para lograr este objetivo se define un enfoque multinivel. La metodología se aplica en tres cuencas con características diferentes. http://hdl.handle.net/2117/19180 Title: Blending of radar and gauge rainfall measurements: a preliminary analysis of the impact of radar errors Authors: Sempere Torres, Daniel; Berenguer Ferrer, Marc; Velasco Forero, Carles Abstract: Several methodologies have been proposed to combine radar and raingauge measurements with the aim of generating improved quantitative precipitation estimates (QPEs). These methods are based on interpolating point raingauge measurements (implicitly assumed to be “the truth”) and benefiting from the structure of the rainfall field as depicted by the radar. The use of a non-parametric approach based on radar measurements has been recently demonstrated, showing the benefits in the interpolation of raingauge measurements under the hypotheses of the Kriging approach. Several experiments have been carried out over a large number of cases and a variety of regions, Kriging with an external drift (i.e. the radar description of the rainfall field) being the approach showing more robust and (overall) better performance. Here, the impact of the discrepancies between two almost-collocated radars on the blended QPE fields was investigated. Mon, 13 May 2013 13:09:06 GMT http://hdl.handle.net/2117/19180 2013-05-13T13:09:06Z Sempere Torres, Daniel; Berenguer Ferrer, Marc; Velasco Forero, Carles no QPE, radar-raingauge blending, spatial variability of rainfall, radar errors, radar calibration Several methodologies have been proposed to combine radar and raingauge measurements with the aim of generating improved quantitative precipitation estimates (QPEs). These methods are based on interpolating point raingauge measurements (implicitly assumed to be “the truth”) and benefiting from the structure of the rainfall field as depicted by the radar. The use of a non-parametric approach based on radar measurements has been recently demonstrated, showing the benefits in the interpolation of raingauge measurements under the hypotheses of the Kriging approach. Several experiments have been carried out over a large number of cases and a variety of regions, Kriging with an external drift (i.e. the radar description of the rainfall field) being the approach showing more robust and (overall) better performance. Here, the impact of the discrepancies between two almost-collocated radars on the blended QPE fields was investigated. http://hdl.handle.net/2117/19166 Title: Stiff clays and mudstones: fundamentals, progressive failure and deep underground excavations Authors: Gens Solé, Antonio Abstract: The subject of this contribution is the hydromechanical behaviour of stiff clays and mudstones, i.e. geological materials in which fine grained particles predominate. It is especially focussed on argillaceous materials that are intermediate between soils and rocks not only with respect to strength but also in terms of porosity and compressibility. Because of space limitations, only sorne salient aspects of the behaviour are outlined herein. First, sorne general aspects of the mechanical behaviour are high1ighted, afterwards the issues of brittleness and progressive failure are addressed and finally sorne observations of their hydromechanical response in underground excavations are presented. Fri, 10 May 2013 15:01:18 GMT http://hdl.handle.net/2117/19166 2013-05-10T15:01:18Z Gens Solé, Antonio no The subject of this contribution is the hydromechanical behaviour of stiff clays and mudstones, i.e. geological materials in which fine grained particles predominate. It is especially focussed on argillaceous materials that are intermediate between soils and rocks not only with respect to strength but also in terms of porosity and compressibility. Because of space limitations, only sorne salient aspects of the behaviour are outlined herein. First, sorne general aspects of the mechanical behaviour are high1ighted, afterwards the issues of brittleness and progressive failure are addressed and finally sorne observations of their hydromechanical response in underground excavations are presented. http://hdl.handle.net/2117/18981 Title: Optimal reconstruction of non-symmetric travel time density distributions using a new kernel density estimator Authors: Pedretti, Daniele; Fernández García, Daniel Thu, 25 Apr 2013 10:44:31 GMT http://hdl.handle.net/2117/18981 2013-04-25T10:44:31Z Pedretti, Daniele; Fernández García, Daniel no http://hdl.handle.net/2117/18980 Title: Modelling of multiphase flow in evaporation tests in concrete columns Authors: Chaparro Sánchez, Maria Carme; Saaltink, Maarten Willem; Villar, M.V. Thu, 25 Apr 2013 08:34:58 GMT http://hdl.handle.net/2117/18980 2013-04-25T08:34:58Z Chaparro Sánchez, Maria Carme; Saaltink, Maarten Willem; Villar, M.V. no http://hdl.handle.net/2117/18936 Title: Failure mechanisms in brittle soils: a dam failure revisited with the material point method Authors: Alonso Pérez de Agreda, Eduardo; Zabala, Francisco Abstract: The material Point Method (MPM) combines features of Finite Element and Discrete Particle methods. It is well suited to analyze geotechnical problems which involve large displacements and dynamic response. An explicit coupled hydro-mechanical formulation has been developed to analyze cases controlled by general loading and pore pressure generation and dissipation. The procedure has been successfully applied to reproduce the failure conditions of Aznalcóllar dam. The failure was explained by a combination of a slow dissipation of pore water pressures in impervious, high plasticity brittle clay and by a progressive failure mechanism. It was also found that the initial state of stress controlled the development and position of the failure surface. Taking Aznalcóllar as a reference case, the following aspects have been investigated: The response of brittle and non-brittle soils; the effect of a sudden loss of effective cohesion at peak strength conditions and the construction sequence and the dam geometry. The analysis of results provides a valuable insight into the significance of the set of aspects outlined above. Mon, 22 Apr 2013 18:46:35 GMT http://hdl.handle.net/2117/18936 2013-04-22T18:46:35Z Alonso Pérez de Agreda, Eduardo; Zabala, Francisco no Material Point Method, progressive failure, strain softening, dam, failure, case history The material Point Method (MPM) combines features of Finite Element and Discrete Particle methods. It is well suited to analyze geotechnical problems which involve large displacements and dynamic response. An explicit coupled hydro-mechanical formulation has been developed to analyze cases controlled by general loading and pore pressure generation and dissipation. The procedure has been successfully applied to reproduce the failure conditions of Aznalcóllar dam. The failure was explained by a combination of a slow dissipation of pore water pressures in impervious, high plasticity brittle clay and by a progressive failure mechanism. It was also found that the initial state of stress controlled the development and position of the failure surface. Taking Aznalcóllar as a reference case, the following aspects have been investigated: The response of brittle and non-brittle soils; the effect of a sudden loss of effective cohesion at peak strength conditions and the construction sequence and the dam geometry. The analysis of results provides a valuable insight into the significance of the set of aspects outlined above. http://hdl.handle.net/2117/18935 Title: A study of the effects of suction and roughness on the mechanical behaviour of rock joints Authors: Zandarín, Maria Teresa; Alonso Pérez de Agreda, Eduardo; Olivella Pastallé, Sebastià Abstract: The experimental investigation focused on the effects of suction on the mechanical behaviour of rock joints. Available experimental data on the effect of moisture on joint behaviour is very scarce. Laboratory tests were performed in a direct shear cell equipped with suction control. Suction was imposed using a vapour forced convection circuit connected to the cell and controlled by an air pump. Artificial joints of Lilla claystone were prepared. Joint roughness of varying intensity was created by carving the surfaces in contact in such a manner that rock ridges of different tip angles were formed. Several tests were performed for different values of suction (20, 100 and 200 MPa) and for different values of vertical stress (30, 60 and 150 kPa). A constitutive model including the effects of suction and joints roughness is proposed to simulate the unsaturated behaviour of rock joints. The new constitutive law was incorporated into the FE computer code Code-Bright and experimental results were numerically simulated. Mon, 22 Apr 2013 18:36:57 GMT http://hdl.handle.net/2117/18935 2013-04-22T18:36:57Z Zandarín, Maria Teresa; Alonso Pérez de Agreda, Eduardo; Olivella Pastallé, Sebastià no The experimental investigation focused on the effects of suction on the mechanical behaviour of rock joints. Available experimental data on the effect of moisture on joint behaviour is very scarce. Laboratory tests were performed in a direct shear cell equipped with suction control. Suction was imposed using a vapour forced convection circuit connected to the cell and controlled by an air pump. Artificial joints of Lilla claystone were prepared. Joint roughness of varying intensity was created by carving the surfaces in contact in such a manner that rock ridges of different tip angles were formed. Several tests were performed for different values of suction (20, 100 and 200 MPa) and for different values of vertical stress (30, 60 and 150 kPa). A constitutive model including the effects of suction and joints roughness is proposed to simulate the unsaturated behaviour of rock joints. The new constitutive law was incorporated into the FE computer code Code-Bright and experimental results were numerically simulated. http://hdl.handle.net/2117/18934 Title: Simulating particle breakage and relative humidity effects in rockfill behaviour Authors: Alonso Pérez de Agreda, Eduardo; Tapias, Mauricio; Gili Ripoll, José Antonio Abstract: The paper presents an analysis of the mechanical behaviour of rockfill using the discrete element method. A background reference is the set of results of a few large scale triaxial tests performed at the UPC geotechnical laboratory. In those tests Relative Humidity (RH) was controlled by means of a vapour equilibrium technique. RH is a fundamental aspect in the behaviour of rockfill which has received limited attention in the past. The Relative Humidity within the large pores between rock fragments controls the velocity of crack propagation within the particles. An increase in RH means faster crack propagation and eventually breakage of some particles and subsequent re-arrangement of the granular structure. The basic tool used to simulate some of the tests is the computer code PFC3D. Rockfill particles (they have the size of gravels, typically ranging from 1 cm to 4 cm) were simulated as breakable clusters of 3D balls. Particle breakage occurs in time according to fracture mechanic’s laws. In a parallel study, the development of cracks in time has been examined. This information was taken into account in the numerical analysis to derive criteria for particle breakage. The paper describes the preliminary results of the work in progress. The actual shape of rock gravels has been approximated by means of clusters of spherical particles. Several arrangements, comprising a different number of particles, have been numerically tested. The results of the modelling exercise are encouraging and test results are reasonably well reproduced. The model is fairly general and it has a number of interesting capabilities. Mon, 22 Apr 2013 18:31:44 GMT http://hdl.handle.net/2117/18934 2013-04-22T18:31:44Z Alonso Pérez de Agreda, Eduardo; Tapias, Mauricio; Gili Ripoll, José Antonio no The paper presents an analysis of the mechanical behaviour of rockfill using the discrete element method. A background reference is the set of results of a few large scale triaxial tests performed at the UPC geotechnical laboratory. In those tests Relative Humidity (RH) was controlled by means of a vapour equilibrium technique. RH is a fundamental aspect in the behaviour of rockfill which has received limited attention in the past. The Relative Humidity within the large pores between rock fragments controls the velocity of crack propagation within the particles. An increase in RH means faster crack propagation and eventually breakage of some particles and subsequent re-arrangement of the granular structure. The basic tool used to simulate some of the tests is the computer code PFC3D. Rockfill particles (they have the size of gravels, typically ranging from 1 cm to 4 cm) were simulated as breakable clusters of 3D balls. Particle breakage occurs in time according to fracture mechanic’s laws. In a parallel study, the development of cracks in time has been examined. This information was taken into account in the numerical analysis to derive criteria for particle breakage. The paper describes the preliminary results of the work in progress. The actual shape of rock gravels has been approximated by means of clusters of spherical particles. Several arrangements, comprising a different number of particles, have been numerically tested. The results of the modelling exercise are encouraging and test results are reasonably well reproduced. The model is fairly general and it has a number of interesting capabilities.