Articles de revista
http://hdl.handle.net/2117/3577
2016-05-25T17:22:38ZDiscussion on “Large landslides associated with a diapiric fold in Canelles reservoir (Spanish Pyrenees): Detailed geological–geomorphological mapping, trenching and electrical resistivity imaging” by Gutiérrez et al. (2015)
http://hdl.handle.net/2117/86976
Discussion on “Large landslides associated with a diapiric fold in Canelles reservoir (Spanish Pyrenees): Detailed geological–geomorphological mapping, trenching and electrical resistivity imaging” by Gutiérrez et al. (2015)
Pinyol Puigmartí, Núria Mercè; Alonso Pérez de Agreda, Eduardo; Corominas Dulcet, Jordi; Moya Sánchez, José
This discussion a) reviews the geological model adopted for the landslide analysis and argues that there is nothing new in the reference paper, b) examines the conditions for fast catastrophic sliding and demonstrates that conditions for such a phenomenon may be present in the case of Canelles slide, against the opinion of the authors, and c) justifies the corrective measures adopted to stabilize the landslide.
2016-05-11T18:48:10ZPinyol Puigmartí, Núria MercèAlonso Pérez de Agreda, EduardoCorominas Dulcet, JordiMoya Sánchez, JoséThis discussion a) reviews the geological model adopted for the landslide analysis and argues that there is nothing new in the reference paper, b) examines the conditions for fast catastrophic sliding and demonstrates that conditions for such a phenomenon may be present in the case of Canelles slide, against the opinion of the authors, and c) justifies the corrective measures adopted to stabilize the landslide.Hydrogeological impact assessment by tunnelling at sites of high sensitivity
http://hdl.handle.net/2117/86876
Hydrogeological impact assessment by tunnelling at sites of high sensitivity
Pujades Garnes, Estanislao; Vázquez Suñé, Enric; Culi, Laura; Carrera Ramírez, Jesús; Ledesma Villalba, Alberto; Jurado Elices, Anna
A tunnel for the High Speed Train (HST) was constructed in Barcelona with an Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM). The tunnel crosses Barcelona and passes under some famous landmarks such as the Sagrada Familia and the Casa Mill Both monuments are UNESCO world heritage sites and a committee appointed by the UNESCO acted as external observers during the construction. Concerns about soil settlements and the hydrogeological impacts of the construction were raised. These concerns were addressed during the design stage to forestall any unexpected events. The methodology consisted of 1) characterising the geology in detail, 2) predicting the impacts caused in the aquifer, 3) predicting the soil displacements due to water table oscillations produced by the construction, and 4) monitoring the evolution of groundwater and soil settlements. The main estimated impact on groundwater was a moderate barrier effect. The barrier effect, the magnitude of which matched the predictions, was detected during construction. The monitoring of soil settlements revealed short and long term movements. The latter movements matched the analytical predictions of soil displacements caused by the groundwater oscillations. This paper proposes a realistic procedure to estimate impacts on groundwater during tunnel construction with an EPB. Our methodology will considerably improve the construction of tunnels in urban areas. (C) 2015 Elsevier B.V. All rights reserved.
2016-05-10T12:57:44ZPujades Garnes, EstanislaoVázquez Suñé, EnricCuli, LauraCarrera Ramírez, JesúsLedesma Villalba, AlbertoJurado Elices, AnnaA tunnel for the High Speed Train (HST) was constructed in Barcelona with an Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM). The tunnel crosses Barcelona and passes under some famous landmarks such as the Sagrada Familia and the Casa Mill Both monuments are UNESCO world heritage sites and a committee appointed by the UNESCO acted as external observers during the construction. Concerns about soil settlements and the hydrogeological impacts of the construction were raised. These concerns were addressed during the design stage to forestall any unexpected events. The methodology consisted of 1) characterising the geology in detail, 2) predicting the impacts caused in the aquifer, 3) predicting the soil displacements due to water table oscillations produced by the construction, and 4) monitoring the evolution of groundwater and soil settlements. The main estimated impact on groundwater was a moderate barrier effect. The barrier effect, the magnitude of which matched the predictions, was detected during construction. The monitoring of soil settlements revealed short and long term movements. The latter movements matched the analytical predictions of soil displacements caused by the groundwater oscillations. This paper proposes a realistic procedure to estimate impacts on groundwater during tunnel construction with an EPB. Our methodology will considerably improve the construction of tunnels in urban areas. (C) 2015 Elsevier B.V. All rights reserved.An Approach to enhance efficiency of DEM modelling of soils with crushable grains
http://hdl.handle.net/2117/86784
An Approach to enhance efficiency of DEM modelling of soils with crushable grains
Ciantia, Matteo; Arroyo Alvarez de Toledo, Marcos; Calvetti, Francesco; Gens Solé, Antonio
In this study oedometric compression tests of hydrocarbon coke, Fontainebleau sand and silica sand are simulated in three dimensions using breakable particles. The method adapts a rigorous breakage criterion for elasto-brittle spheres to represent failure of grains isolated between platens or within granular masses. The breakage criterion allows for the effect of particle bulk and contact properties to be treated separately. A discrete fragmentation multigenerational approach is applied as a spawning procedure. The number of particles quickly increases during the simulation, but is kept manageable by systematic fine exclusion and upscaling. Fine exclusion leads to mass losses between generations, but that loss is accounted for outside the mechanical model. Sensitivity analysis shows that it is enough to keep 53% of the crushed particle mass within the mechanical model to correctly reproduce experimental macroscopic behaviour. Practical upscaling rules are proposed for (a) contact stiffness, (b) breakage criteria and (c) grain size distribution, and validated simulating the same test, reducing by half the initial number of particles. The results are promising as both the mechanical and grading evolution are well captured with two orders of magnitude savings in computing efficiency.
2016-05-09T13:08:27ZCiantia, MatteoArroyo Alvarez de Toledo, MarcosCalvetti, FrancescoGens Solé, AntonioIn this study oedometric compression tests of hydrocarbon coke, Fontainebleau sand and silica sand are simulated in three dimensions using breakable particles. The method adapts a rigorous breakage criterion for elasto-brittle spheres to represent failure of grains isolated between platens or within granular masses. The breakage criterion allows for the effect of particle bulk and contact properties to be treated separately. A discrete fragmentation multigenerational approach is applied as a spawning procedure. The number of particles quickly increases during the simulation, but is kept manageable by systematic fine exclusion and upscaling. Fine exclusion leads to mass losses between generations, but that loss is accounted for outside the mechanical model. Sensitivity analysis shows that it is enough to keep 53% of the crushed particle mass within the mechanical model to correctly reproduce experimental macroscopic behaviour. Practical upscaling rules are proposed for (a) contact stiffness, (b) breakage criteria and (c) grain size distribution, and validated simulating the same test, reducing by half the initial number of particles. The results are promising as both the mechanical and grading evolution are well captured with two orders of magnitude savings in computing efficiency.Internal progressive failure in deep-seated landslides
http://hdl.handle.net/2117/86758
Internal progressive failure in deep-seated landslides
Yerro, Alba; Pinyol Puigmartí, Núria Mercè; Alonso Pérez de Agreda, Eduardo
Except for simple sliding motions, the stability of a slope does not depend only on the resistance of the basal failure surface. It is affected by the internal distortion of the moving mass, which plays an important role on the stability and post-failure behaviour of a landslide. The paper examines the stability conditions and the post-failure behaviour of a compound landslide whose geometry is inspired by one of the representative cross-sections of Vajont landslide. The brittleness of the mobilized rock mass was described by a strain-softening Mohr–Coulomb model, whose parameters were derived from previous contributions. The analysis was performed by means of a MPM computer code, which is capable of modelling the whole instability procedure in a unified calculation. The gravity action has been applied to initialize the stress state. This step mobilizes part of the strength along a shearing band located just above the kink of the basal surface, leading to the formation a kinematically admissible mechanism. The overall instability is triggered by an increase of water level. The increase of pore water pressures reduces the effective stresses within the slope and it leads to a progressive failure mechanism developing along an internal shearing band which controls the stability of the compound slope. The effect of the basal shearing resistance has been analysed during the post-failure stage. If no shearing strength is considered (as predicted by a thermal pressurization analysis), the model predicts a response similar to actual observations, namely a maximum sliding velocity of 25 m/s and a run-out close to 500 m.
2016-05-09T10:19:56ZYerro, AlbaPinyol Puigmartí, Núria MercèAlonso Pérez de Agreda, EduardoExcept for simple sliding motions, the stability of a slope does not depend only on the resistance of the basal failure surface. It is affected by the internal distortion of the moving mass, which plays an important role on the stability and post-failure behaviour of a landslide. The paper examines the stability conditions and the post-failure behaviour of a compound landslide whose geometry is inspired by one of the representative cross-sections of Vajont landslide. The brittleness of the mobilized rock mass was described by a strain-softening Mohr–Coulomb model, whose parameters were derived from previous contributions. The analysis was performed by means of a MPM computer code, which is capable of modelling the whole instability procedure in a unified calculation. The gravity action has been applied to initialize the stress state. This step mobilizes part of the strength along a shearing band located just above the kink of the basal surface, leading to the formation a kinematically admissible mechanism. The overall instability is triggered by an increase of water level. The increase of pore water pressures reduces the effective stresses within the slope and it leads to a progressive failure mechanism developing along an internal shearing band which controls the stability of the compound slope. The effect of the basal shearing resistance has been analysed during the post-failure stage. If no shearing strength is considered (as predicted by a thermal pressurization analysis), the model predicts a response similar to actual observations, namely a maximum sliding velocity of 25 m/s and a run-out close to 500 m.Landslide hazard, monitoring and conservation strategy for the safeguard of Vardzia Byzantine monastery complex, Georgia
http://hdl.handle.net/2117/86756
Landslide hazard, monitoring and conservation strategy for the safeguard of Vardzia Byzantine monastery complex, Georgia
Margottini, Claudio; Corominas Dulcet, Jordi; Crosta, Giovanni Battista; Frattini, Paolo; Gigli, Giovanni; Giordan, Daniele; Iwasaky, Ioshinori; Lollino, Giorgio; Scavia, Claudio; Marinos, Paul; Manconi, A.; Sonessa, A.; Spizzichino, Danielle; Vacheishvili, N.; Antidze, N.
This paper reports preliminary results of a feasibility project developed in cooperation with National Agency for Cultural Heritage Preservation of Georgia, and aimed at envisaging the stability conditions of the Vardzia monastery slope (rupestrian city cave in the south-western Georgia). The aim is the implementation of a low-impact monitoring system together with long-term mitigation/conservation policies. A field analysis was conducted to reconstruct geometry of the rocky cliff, characteristics of discontinuities, main failure modes, and volume of potential unstable blocks and geomechanical parameters. Instability processes are the combination of causative factors such as the following: lithology, frequency and orientation of discontinuities, slope orientation, physical and mechanical characteristics of slope-forming materials, and morphological and hydrological boundary conditions. The combined adoption of different survey techniques (e.g., 3D laser scanner, ground-based radar interferometry) could be the best solution in the interdisciplinary field of cultural heritage preservation policies. The collected data will be the basis for future activities to be completed in collaboration with local authorities for a complete hazard and risk characterization for the monastery site and the development of an early warning system to allow safe exploitation for touristic activities and for historical site preservation.
2016-05-09T10:03:41ZMargottini, ClaudioCorominas Dulcet, JordiCrosta, Giovanni BattistaFrattini, PaoloGigli, GiovanniGiordan, DanieleIwasaky, IoshinoriLollino, GiorgioScavia, ClaudioMarinos, PaulManconi, A.Sonessa, A.Spizzichino, DanielleVacheishvili, N.Antidze, N.This paper reports preliminary results of a feasibility project developed in cooperation with National Agency for Cultural Heritage Preservation of Georgia, and aimed at envisaging the stability conditions of the Vardzia monastery slope (rupestrian city cave in the south-western Georgia). The aim is the implementation of a low-impact monitoring system together with long-term mitigation/conservation policies. A field analysis was conducted to reconstruct geometry of the rocky cliff, characteristics of discontinuities, main failure modes, and volume of potential unstable blocks and geomechanical parameters. Instability processes are the combination of causative factors such as the following: lithology, frequency and orientation of discontinuities, slope orientation, physical and mechanical characteristics of slope-forming materials, and morphological and hydrological boundary conditions. The combined adoption of different survey techniques (e.g., 3D laser scanner, ground-based radar interferometry) could be the best solution in the interdisciplinary field of cultural heritage preservation policies. The collected data will be the basis for future activities to be completed in collaboration with local authorities for a complete hazard and risk characterization for the monastery site and the development of an early warning system to allow safe exploitation for touristic activities and for historical site preservation.Ageing effects on the small-strain stiffness of a bio-treated compacted soil
http://hdl.handle.net/2117/86750
Ageing effects on the small-strain stiffness of a bio-treated compacted soil
Morales, Laura; Romero Morales, Enrique Edgar; Jommi, Cristina; Garzón Garzón, Eduardo; Giménez, Antonio
The effect of ageing on the small-strain shear stiffness of compacted silty-clayey sand following a ‘soft’ biological treatment is discussed. Samples were prepared by static compaction, adding urea-degrading bacteria to the compaction water. No nutrients were artificially added, relying on the natural availability of urea and calcium ions (Ca2 +) in the humic soil and in the compaction water for the bacteria to precipitate calcium carbonate. After compaction, to replicate different environmental boundary conditions, some of the samples were cured in a system open to vapour transfer and some were cured in a closed system. The small-strain shear stiffness was periodically tracked with bender elements during the ageing period. Tests were run in parallel to investigate the unconfined compression strength, the water retention properties and soil pore size distribution changes during ageing. The test results revealed a small but consistent increase in the small-strain shear stiffness during the ageing period due to the microbiological treatment, in both the closed and open systems. In the latter case, the contribution of the microbiological treatment to the increase in stiffness could be estimated after correcting the data for the suction increase due to evaporation.
2016-05-09T09:26:06ZMorales, LauraRomero Morales, Enrique EdgarJommi, CristinaGarzón Garzón, EduardoGiménez, AntonioThe effect of ageing on the small-strain shear stiffness of compacted silty-clayey sand following a ‘soft’ biological treatment is discussed. Samples were prepared by static compaction, adding urea-degrading bacteria to the compaction water. No nutrients were artificially added, relying on the natural availability of urea and calcium ions (Ca2 +) in the humic soil and in the compaction water for the bacteria to precipitate calcium carbonate. After compaction, to replicate different environmental boundary conditions, some of the samples were cured in a system open to vapour transfer and some were cured in a closed system. The small-strain shear stiffness was periodically tracked with bender elements during the ageing period. Tests were run in parallel to investigate the unconfined compression strength, the water retention properties and soil pore size distribution changes during ageing. The test results revealed a small but consistent increase in the small-strain shear stiffness during the ageing period due to the microbiological treatment, in both the closed and open systems. In the latter case, the contribution of the microbiological treatment to the increase in stiffness could be estimated after correcting the data for the suction increase due to evaporation.Analysis of slope movement initiation induced by rainfall using the Elastoplastic Barcelona Basic Model
http://hdl.handle.net/2117/86701
Analysis of slope movement initiation induced by rainfall using the Elastoplastic Barcelona Basic Model
Jamei, M.; Guiras, H.; Olivella Pastallé, Sebastià
In some arid and semi-arid regions, different types of infrastructure assets suffer from degradation of the roads, the embankment failures, erosion due to cyclic hydraulic actions and the effects of rainfall infiltration on slopes. Typical cases, such as the national roads in the north-west of Tunisia (Beja city) have been affected dramatically. Recent landslide is manifested in this region, especially in a plastic clay soil. Stability problems are caused by soil saturation and the presence of abundant cracks which are developed after a long dry summer. In fact, due to geotechnical problems, the annual loss due to the damage is estimated at $1 million in Beja area (30 km(2)). The effect of rainfall infiltration into the unsaturated clay during wet seasons characterised by either long duration low intensity rain or short duration high intensity rain have been analysed. The elastoplastic Barcelona Basic Model (BBM) has been used and soil movements leading to slope failure were calculated according to the unsaturated state evolution. The effects of cyclic hydraulic paths on the yield function have also been investigated. The yield function evolution depends on the cohesion and the apparent consolidation stress variations. The numerical calculations were evaluated against the field measurement displacements.
2016-05-06T12:52:02ZJamei, M.Guiras, H.Olivella Pastallé, SebastiàIn some arid and semi-arid regions, different types of infrastructure assets suffer from degradation of the roads, the embankment failures, erosion due to cyclic hydraulic actions and the effects of rainfall infiltration on slopes. Typical cases, such as the national roads in the north-west of Tunisia (Beja city) have been affected dramatically. Recent landslide is manifested in this region, especially in a plastic clay soil. Stability problems are caused by soil saturation and the presence of abundant cracks which are developed after a long dry summer. In fact, due to geotechnical problems, the annual loss due to the damage is estimated at $1 million in Beja area (30 km(2)). The effect of rainfall infiltration into the unsaturated clay during wet seasons characterised by either long duration low intensity rain or short duration high intensity rain have been analysed. The elastoplastic Barcelona Basic Model (BBM) has been used and soil movements leading to slope failure were calculated according to the unsaturated state evolution. The effects of cyclic hydraulic paths on the yield function have also been investigated. The yield function evolution depends on the cohesion and the apparent consolidation stress variations. The numerical calculations were evaluated against the field measurement displacements.Thermo-poro-mechanical analysis of landslides: from creeping behaviour to catastrophic failure
http://hdl.handle.net/2117/86648
Thermo-poro-mechanical analysis of landslides: from creeping behaviour to catastrophic failure
Alonso Pérez de Agreda, Eduardo; Zervos, Antonis; Pinyol Puigmartí, Núria Mercè
The scope of the paper encompasses planar and compound sliding motions, which may exhibit creeping behaviour during a certain period but may evolve to a very rapid motion. Thermo-mechanical interactions, at the scale of the sliding surface, are accepted as a critical aspect to explain these motion phases and their relationship. The sliding kinetics and global equilibrium are described at a large scale and the evolving shearing strength at the sliding surface derives from the local analysis of the shearing band and its vicinity. Pore pressures, temperatures and related variables are calculated by resolving a set of balance equations. The paper describes the transition from creeping motions to a rapid event. Results are found in terms of dimensionless numbers. Calculation of the slide evolution requires special numerical techniques described in the paper. Band permeability is found to be the dominant property controlling the triggering of fast motions. The creeping stage and the eventual slide blow-up are intimately linked. This relationship is explored in the paper. The models presented can be readily used to back-analyse relevant case histories or, in principle, even to carry out predictive modelling, provided an adequate calibration is available for the material parameters.
2016-05-05T14:08:34ZAlonso Pérez de Agreda, EduardoZervos, AntonisPinyol Puigmartí, Núria MercèThe scope of the paper encompasses planar and compound sliding motions, which may exhibit creeping behaviour during a certain period but may evolve to a very rapid motion. Thermo-mechanical interactions, at the scale of the sliding surface, are accepted as a critical aspect to explain these motion phases and their relationship. The sliding kinetics and global equilibrium are described at a large scale and the evolving shearing strength at the sliding surface derives from the local analysis of the shearing band and its vicinity. Pore pressures, temperatures and related variables are calculated by resolving a set of balance equations. The paper describes the transition from creeping motions to a rapid event. Results are found in terms of dimensionless numbers. Calculation of the slide evolution requires special numerical techniques described in the paper. Band permeability is found to be the dominant property controlling the triggering of fast motions. The creeping stage and the eventual slide blow-up are intimately linked. This relationship is explored in the paper. The models presented can be readily used to back-analyse relevant case histories or, in principle, even to carry out predictive modelling, provided an adequate calibration is available for the material parameters.Benchmarking selection of parameter values for the Barcelona basic model
http://hdl.handle.net/2117/86568
Benchmarking selection of parameter values for the Barcelona basic model
D'Onza, Francesca; Wheeler, S. J.; Gallipoli, Domenico; Hofmann, M.; Lloret Cabot, Marti; Lloret Morancho, Antonio; Mancuso, C.; Pereira, J.M.; Romero Morales, Enrique Edgar; Toll, D. G.; Vassallo, R.
Seven teams took part in a benchmarldng exercise on selection of parameter values for the Barcelona Basic Model (BBM) from experimental data on an unsaturated soil. All teams were provided with experimental results from 9 tests performed on a compacted soil in order to determine values for the ten BBM soil constants and an initial value for the hardening parameter. The coordinating team then performed simulations (at stress point level) with the 7 different sets of parameter values, in order to explore the implications of the differences in parameter values and hence to investigate the robustness of existing BBM parameter value selection procedures. The major challenge was found to be selection of values for the constants lambda(0), r, beta, N(0) and p(c) and an initial value for the hardening parameter (p) over bar (0)(0), with the various teams proposing significantly different values for some of these key parameters. A key lesson emerging from the exercise is the importance of choosing a method for selecting values for the parameters beta and p(c) which places the main emphasis on attempting to optimise the match to the experimental spacing of normal compression lines at different values of suction. (C) 2015 Elsevier B.V. All rights reserved.
2016-05-04T12:51:48ZD'Onza, FrancescaWheeler, S. J.Gallipoli, DomenicoHofmann, M.Lloret Cabot, MartiLloret Morancho, AntonioMancuso, C.Pereira, J.M.Romero Morales, Enrique EdgarToll, D. G.Vassallo, R.Seven teams took part in a benchmarldng exercise on selection of parameter values for the Barcelona Basic Model (BBM) from experimental data on an unsaturated soil. All teams were provided with experimental results from 9 tests performed on a compacted soil in order to determine values for the ten BBM soil constants and an initial value for the hardening parameter. The coordinating team then performed simulations (at stress point level) with the 7 different sets of parameter values, in order to explore the implications of the differences in parameter values and hence to investigate the robustness of existing BBM parameter value selection procedures. The major challenge was found to be selection of values for the constants lambda(0), r, beta, N(0) and p(c) and an initial value for the hardening parameter (p) over bar (0)(0), with the various teams proposing significantly different values for some of these key parameters. A key lesson emerging from the exercise is the importance of choosing a method for selecting values for the parameters beta and p(c) which places the main emphasis on attempting to optimise the match to the experimental spacing of normal compression lines at different values of suction. (C) 2015 Elsevier B.V. All rights reserved.The material point method for unsaturated soils
http://hdl.handle.net/2117/85081
The material point method for unsaturated soils
Yerro Colom, Alba; Alonso Pérez de Agreda, Eduardo; Pinyol Puigmartí, Núria Mercè
The paper describes a three-phase single-point material point method formulation of coupled flow (water and air) for hydro-mechanical analysis of geotechnical problems involving unsaturated soils. The governing balance and dynamic momentum equations are discretised and adapted to material point method characteristics: an Eulerian computational mesh and a Lagrangian analysis of material points. General mathematical expressions for the terms of the set of governing equations are given. A suction-dependent elastoplastic Mohr-Coulomb model, expressed in terms of net stress and suction variables is implemented. The instability of a slope subjected to rain infiltration, inspired from a real case, is solved and discussed. The model shows the development of the initial failure surface in a region of deviatoric strain localisation, the evolution of stress and suction states in some characteristic locations, the progressive large strain deformation of the slope and the dynamics of the motion characterised by the history of displacement, velocity and acceleration of the unstable mass.
2016-04-01T15:05:01ZYerro Colom, AlbaAlonso Pérez de Agreda, EduardoPinyol Puigmartí, Núria MercèThe paper describes a three-phase single-point material point method formulation of coupled flow (water and air) for hydro-mechanical analysis of geotechnical problems involving unsaturated soils. The governing balance and dynamic momentum equations are discretised and adapted to material point method characteristics: an Eulerian computational mesh and a Lagrangian analysis of material points. General mathematical expressions for the terms of the set of governing equations are given. A suction-dependent elastoplastic Mohr-Coulomb model, expressed in terms of net stress and suction variables is implemented. The instability of a slope subjected to rain infiltration, inspired from a real case, is solved and discussed. The model shows the development of the initial failure surface in a region of deviatoric strain localisation, the evolution of stress and suction states in some characteristic locations, the progressive large strain deformation of the slope and the dynamics of the motion characterised by the history of displacement, velocity and acceleration of the unstable mass.