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  • Ventilation effects in an argillaceous rock tunnel examined via unsaturated soil mechanics

     Gens Sole, Antonio; Garitte, Benoit
    Pan-American Conference on Unsaturated Soils
    Presentation's date: 2013-02
    Presentation of work at congresses

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    The paper presents the observations, analysis and interpretation of a long-term ventilation test performed in the Mont Terri underground laboratory. An unlined 1.3 m diameter tunnel excavated in Opalinus clay has been subjected to two controlled ventilation periods. Extensive instrumentation has provided observations concerning relative humidity, pore pressures and displacements in the rock. In addition, boreholes have been drilled at several times during the experiment to obtain independent measurements of water content and degree of saturation of the rock. It has been found that an unsaturated zone surrounding the tunnel, though small in extent, largely controls the progress of drying and other effects associated with ventilation. The interpretation of the test has been based on a coupled multi-phase hydromechanical numerical model in which unsaturated soil mechanics concepts such as vapour diffusion, relative permeability and retention curve play a paramount role. 2013 Taylor Francis Group, London.

  • Analysis of hydro-mechanical processes in a ventilated tunnel in an argillaceous rock on the basis of different modelling approaches

     Garitte, Benoit; Bond, A.; Millard, A.; Zhang, C.; Mcdermott, C.; Nakama, S.; Gens Sole, Antonio
    Journal of rock mechanics and geotechnical engineering
    Date of publication: 2013-02
    Journal article

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    In this paper, a modelling benchmark exercise from the DECOVALEX-2011 project is presented. The benchmark is based on the performance and results of a laboratory drying test and of the ventilation experiment (VE) carried out in the Mont Terri Underground Rock Laboratory (URL). Both tests involve Opalinus clay. The work aims at the identification, understanding and quantification of mechanisms taking place during the ventilation of a gallery in argillaceous host rocks on one hand and at investigating the capacity of different codes and individuals to reproduce these processes on the other hand. The 4-year in situ VE took place in a 1.3 m diameter unlined tunnel and included two resaturation¿desaturation cycles. The test area was equipped with over one hundred sensors (including the global water mass balance of the system, relative humidity (RH), water content, liquid pressure, relative displacement and concentration of some chemical species) to monitor the rock behaviour during ventilation. The laboratory drying experiment, carried out before the VE, was designed to mimic the in situ conditions. The work was organized in a progressive manner in terms of complexity of the computations to be performed, geared towards the full hydro-mechano-chemical (HMC) understanding of the VE, the final objective. The main results from the modelling work reported herein are that the response of the host rock to ventilation in argillaceous rocks is mainly governed by hydraulic processes (advective Darcy flow and non-advective vapour diffusion) and that the hydro-mechanical (TM) back coupling is weak. A ventilation experiment may thus be regarded as a large scale-long time pump test and it is used to determine the hydraulic conductivity of the rock mass.

  • Thermal conductivity of argillaceous rocks: determination methodology using in situ heating tests

     Garitte, Benoit; Gens Sole, Antonio; Vaunat, Jean; Gilles, Armand
    Rock mechanics and rock engineering
    Date of publication: 2012-11-12
    Journal article

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    This study focuses on the characterisation of thermal conductivity for three potential host rocks for radioactive waste disposal. First, the heat conduction process is reviewed on the basis of an analytical solution and key aspects related to anisotropic conduction are discussed. Then the existing information on the three rocks is summarised and a broad uncertainty range of thermal conductivity is estimated based on the mineralogical composition. Procedures to backanalyse the thermal conductivity on the basis of in situ heating tests are assessed and a methodology is put forward. Finally, this methodology is used to estimate the impact of experimental uncertainties and applied to the four in situ heating tests. In the three potential host rocks, a clear influence of the bedding planes was identified and anisotropic heat conduction was shown to be necessary to interpret the observed temperature field. Experimental uncertainties were also shown to induce a larger uncertainty on the anisotropy ratio than on the equivalent thermal conductivity defined as the geometric mean of the thermal conductivity in the three principal directions.

  • Behaviour of the Callovo-Oxfordian clay around a converging heated borehole : thermal free wall experiment

     Garitte, Benoit; Gens Sole, Antonio; Vaunat, Jean; Armand, G.; Conil, N.
    International Meeting on Clays in Natural and Engineered Barriers for Radioactive Waste Confinement
    Presentation's date: 2012
    Presentation of work at congresses

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  • In situ behaviour of opalinus clay under thermal loading

     Gens Sole, Antonio; Garitte, Benoit; Vaunat, Jean
    EAGE Shale Workshop
    Presentation's date: 2012-01
    Presentation of work at congresses

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  • Analysis of the temperature and pore water pressure field in the ted heating experiment

     Garitte, Benoit; Conil, N.; Vaunat, Jean; Gens Sole, Antonio; Armand, G.
    International Meeting on Clays in Natural and Engineered Barriers for Radioactive Waste Confinement
    Presentation's date: 2012
    Presentation of work at congresses

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  • Pore water pressure response to small and large openings in argillaceous rocks

     Garitte, Benoit; Gens Sole, Antonio; Vaunat, Jean; Armand, G.; Conil, N.
    International Meeting on Clays in Natural and Engineered Barriers for Radioactive Waste Confinement
    Presentation's date: 2012
    Presentation of work at congresses

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  • The response of an argillaceous rock to ventilation : process identification and analysis of an in situ experiment

     Garitte, Benoit; Gens Sole, Antonio
    ISRM European Rock Mechanics Symposium
    Presentation's date: 2011-10
    Presentation of work at congresses

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    3D Interpretation of an in situ heating test in the callovo-oxfordian mudstone  Open access

     Garitte, Benoit; Vaunat, Jean; Gens Sole, Antonio; Armand, G.
    International Meeting on Clays in Natural and Engineered Barriers for Radioactive Waste Confinement
    Presentation's date: 2010
    Presentation of work at congresses

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    In order to improve the understanding of the thermo-hydro-mechanical (THM) behaviour of the Callovo-Oxfordian Clay, an in situ heating test (TER experiment) has been realized by ANDRA at Meuse/Haute Marne URL during the last years. In this experiment, one power-control heater has been placed in a horizontal borehole and several heating phases realized at distinct levels of power. Around this heating borehole, 32 temperature sensors, 5 water pressure sensors and 2 extensometers were placed in 8 different boreholes. This abstract presents the interpretation works performed in parallel by running 3D THM simulations.

  • Analysis of ground movements induced by diaphragm wall installation

     Garitte, Benoit; Arroyo Alvarez de Toledo, Marcos; Gens Sole, Antonio
    European Conference on Numerical Methods in Geotechnical Engineering
    Presentation's date: 2010-06
    Presentation of work at congresses

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    The construction process of diaphragm walls can lead to movements in the surrounding area that are seldom taken into account. However, these movements may be important in situations where soft soils dominate. In this paper, after briefly reviewing the state of the art on this issue, we present results of a hydromechanical simulation of the problem in a case located in deltaic soils of Barcelona. The auscultation record of the settlements of a nearby building is employed to validate the computational model. Panel length and bentonite slurry level were found to be the most influent parameters on induced displacements.

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    Predictive modelling of an excavation test in indurated clay  Open access

     Garitte, Benoit; Vaunat, Jean; Gens Sole, Antonio; Vietor, Tim
    International Meeting on Clays in Natural and Engineered Barriers for Radioactive Waste Confinement
    Presentation's date: 2010
    Presentation of work at congresses

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    This abstract presents the predictive hydromechanical (HM) modelling of an excavation performed in Opalinus clay in the Mont Terri underground laboratory.

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    Applications of multiphysical geomechanics in underground nuclear waste storage  Open access

     Gens Sole, Antonio; Garitte, Benoit; Olivella Pastalle, Sebastian; Vaunat, Jean
    European journal of environmental and civil engineering
    Date of publication: 2009
    Journal article

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    Deep geological disposal in suitable host rocks is the favoured strategy for the storage and disposal of heat-emitting high level nuclear waste. A rational design of repositories requires a good understanding of the interacting thermo-hydro-mechanical phenomena that occur in the engineered barrier and adjacent rock. To this end, a multiphysical formulation is described that allows the performance of coupled THM analyses capable of reproducing observed phenomena. The formulation and computer code is applied to the simulation of two large scale tests: a mine-by test involving the excavation of a shaft in an argillaceous rock and a large-scale high- temperature heating test in fractured rock.

    Postprint (author’s final draft)

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

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

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  • Class A prediction of a mine-by test in an overconsolidated mudstone

     Garitte, Benoit; Vaunat, Jean; Gens Sole, Antonio; Vietor, Tim
    International Conference on Computational Methods in Tunnelling
    Presentation's date: 2009
    Presentation of work at congresses

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    In this paper, 3D HM computations are performed to predict the rock response during the excavation of a new gallery (mine-by test) realized in Opalinus clay at the Mont- Terri laboratory, Switzerland. In a first part, previous mine-by tests in similar materials are reviewed: the CLIPEX experiment in Mol (Belgium, Boom clay), the MODEX-REP experiment in Meuse Haute Marne laboratory (France, Callovo-Oxfordian Clay) and the ED-B at Mont Terri (Switzerland, Opalinus Clay). Possible relevant processes are identified. Secondly, the hydro-mechanical formulation used to reproduce the test is described. Thirdly, a 3D HM model adapted to the investigated mine-by test is set up. This model accounts for the anisotropy of the initial stress state and hydro-mechanical material properties (stiffness and permeability). Finally, the influence of anisotropy of stress state and stiffness are investigated by means of a sensitivity analysis.

  • A DECOVALEX-2011 benchmark: laboratory drying test in opalinus clay

     Garitte, Benoit; Gens Sole, Antonio; Liu, Quansheng; Liu, Xiaoyan; Millard, Alain; Bond, Alex; McDermott, Chris; Fujita, Tomoo; Nakatama, Shigeo
    TIMODAZ-THERESA lnternational Conference
    Presentation's date: 2009-10
    Presentation of work at congresses

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    In this paper, a benchmark exercise from the DECOVALEX-2011 project is presented. Experimental results from a laboratory drying test in Opalinus Clay are used. First, the DECO- V ALEX project and the teams of the benchmark are introduced and the experimental setup of the laboratory drying test is described. Then the theoretical formulations and the parameters determination are explained. Finally, the modelling results obtained by the five different teams are compared to the measurements.

  • Comparative study of three in-situ heating tests of anisotropic media: the HE-D, TER and ATLAS experiments

     Garitte, Benoit; Sillen, X.; Li, XiangLing; Gilles, Armand; Vaunat, Jean; Gens Sole, Antonio
    Impact of thermo-hydro-mechanical-chemical (THMC) processes on the safety of underground radioactive waste repositories
    Presentation's date: 2009-10
    Presentation of work at congresses

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    The paper presents an interpretation ofthe Thermo-Hydro-Mechanical (THM) behaviour of three clays in three in-situ heating tests. First, the in-situ measurements are explored and common rock features are identified. Then a 3D THM model is set up for each ofthe tests and the HM response induced by the drilling of the heating boreholes as well as the THM response during the heating phase are discussed.

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    Thermo-hydro-mechanical response of an argillaceous rock: experimental results and modelling  Open access

     Garitte, Benoit; Vaunat, Jean; Gens Sole, Antonio
    International Conference on Computational Plasticity Fundamentals and Applications
    Presentation's date: 2009-09-02
    Presentation of work at congresses

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    This extended abstract presents the key features of a THM analysis carried out to analyze the thermo-hydro-mechanical response of a mudstone under thermal loading. The analysis was performed in parallel with a large scale heating test. The good agreement observed between the measurements and the numerical results provides an incomparable validation of the model.

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    Hydraulic response to a shaft excavation in Callovo-Oxfordian clay  Open access

     Garitte, Benoit; Gens Sole, Antonio; Vaunat, Jean; Armand, Gilles
    International Conference on Computational Methods for Coupled Problems in Science and Engineering
    Presentation's date: 2009-06-08
    Presentation of work at congresses

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    This document presents a coupled hydro-mechanical (HM) numerical analysis,using Code_Bright, simulating the excavation of the main access shaft to the underground laboratory of Bure (France) in Callovo-Oxfordian Clay. The work consists in the description of the HM formulation using a specially developed constitutive law and in the discussion of the simulation results. The mechanisms at the origin of the water pressure response are analysed with special emphasis on the influence of the mechanical and hydraulic boundary conditions used for the shaft excavation. Shaft convergence and permeability evolution measured by ANDRA (Modex-REP mine-by-test, [1,2]) during the shaft excavation are compared with the modelling results to illustrate the model capability to reproduce excavation induced damage and to relate it to permeability increase.

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    Modelling of a deep excavation in a stiff clay  Open access

     Vaunat, Jean; Garitte, Benoit; Gens Sole, Antonio
    International Conference on Computational Plasticity Fundamentals and Applications
    Presentation's date: 2009
    Presentation of work at congresses

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    This extended abstract presents an interpretation of the response of a mudstone during the excavation of a shaft at high depths (500m). Instrument layout and numerical model are described. A very good agreement is observed between the field measurements and computed values.

  • Coupled THM problems in geotechnical engineering using code_bright gid

     Pinyol Puigmarti, Nuria Merce; Olivella Pastalle, Sebastian; Garitte, Benoit; Vaunat, Jean
    Conference on Advances and Applications on GiD
    Presentation's date: 2008-05-08
    Presentation of work at congresses

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    In situ behaviour of a stiff layered clay subject to thermal loading: Observations and interpretation  Open access  awarded activity

     Gens Sole, Antonio; Vaunat, Jean; Garitte, Benoit; Wileveau, Y
    Géotechnique
    Date of publication: 2007-03
    Journal article

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    The paper presents an interpretation of an in situ heating test carried out on Opalinus clay in the Mont Terri underground laboratory. Opalinus clay is a stiff, strongly bedded, Mesozoic clay of marine origin. When subjected to thermal loading, saturated stiff clays exhibit a strong pore pressure response that significantly affects the hydraulic and mechanical behaviour of the material. The observations gathered in the in situ test have provided an opportunity to examine the integrated thermo-hydro-mechanical (THM) response of this sedimentary clay. Coupled THM numerical analyses have been carried out to provide a structured framework for interpretation, and to enhance understanding of THM clay behaviour. Numerical analyses have been based on a coupled theoretical formulation that incorporates a constitutive law especially developed for this type of material. The law includes degradation of bonding by damage. By performing three-dimensional computations, it has been possible to incorporate anisotropy of material parameters and of in situ stresses. The 3D simulation has proved able to furnish a satisfactory representation of the development of the in situ test and of the main observed patterns of behaviour. A sensitivity analysis has also been carried out to examine the potential effect of various key or uncertain parameters. The critical examination of test observations and the results of the numerical analyses have allowed the classification, by differing degrees of significance, of the various coupled phenomena present in the problem.

    George Stephenson Medal 2008, atorgada per la Institution of Civil Engineers del Regne Unit

  • Elastoplastic modelling of hard soils and soft rocks: Formulation and application

     Vaunat, Jean; Garitte, Benoit
    International Conference on Computational Plasticity
    Presentation of work at congresses

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