A thermomechanical model for argillaceous hard soils - weak rocks: application to THM simulation of deep excavations in claystone

Tourchi, Saeed; Malcom, Miguel Manica; Vaunat, Jean; Gens, Antonio

doi:10.31223/x5jh29

Cited by 2 publications

(2 citation statements)

References 46 publications

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“…This implies that larger plastic deformations and a failure surface can be expected under higher temperatures, such as those induced by near-surface ground temperature changes. Following (Tourchi 2020, Tourchi et al 2020, 2022, this behaviour can be incorporated by assuming that the strength parameters also depend on temperature. A hyperbolic Mohr-Coulomb type yield function mainly is characterizes the adopted model; therefore, the strength's dependence on temperature can also be incorporated through the parameters 𝜙 and 𝑐.…”

Section: Thermoplastic Componentsmentioning

confidence: 99%

Thermo-hydro-mechanical analysis of Bentonite at residual state

Tourchi¹,

Loche²,

Scaringi³

2023

Preprint

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This paper presents experimental and numerical investigations regarding the effect of temperature on the residual strength of Bentonite at slow-to-moderate shearing velocities. In order to understand the trigger mechanism of slow-moving landslides, we investigated the effect of temperature on the shear strength of slip surfaces. We performed ring-shear tests on Bentonite samples at various temperatures and rates. The test results show that the residual shear strength of Bentonite is both rate and temperature dependent. Under relatively slow shearing rates, strength was gained as temperature increased; in contrast, under relatively high shearing rates, strength was decreased as temperature increased. A non-isothermal viscoplastic model is proposed to simulate the observed behaviour of a ring- shear samples of Bentonite subjected to drained heating under residual conditions. The developed model was implemented in finite element computer code for THM analysis of porous media, and experimental results were numerically simulated.

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Section: Thermoplastic Componentsmentioning

confidence: 99%

Thermo-hydro-mechanical analysis of Bentonite at residual state

Tourchi¹,

Loche²,

Scaringi³

2023

Preprint

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“…The thermal calculations included in this thesis are an extension of the modelling task reported in Tourchi et al (2019) where the following aspects were investigated:…”

Section: D Thermal Analysismentioning

confidence: 99%

THM analysis of argillaceous rocks with application to nuclear waste underground storage

Tourchi¹

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Argillaceous rocks (Stiff sedimentary clays) provide the geological background to many civil engineering projects. In recent years, interest in these types of material has increased, because they are being considered as potential host geological media for underground repositories of high-level radioactive waste (HLW). The possible use of these types of clay as geological hosts for radioactive waste has prompted the construction of several underground laboratories. Among the very different topics addressed in the Underground Research Laboratories (URLs), the thermo-hydro-mechanical (THM) behaviour of the host rock is the one that most concerns the present research. In situ observations have revealed a considerable number of coupled THM processes in the operation of an HLW repository. In this context, the main objective of the present study is to describes the performance, observations and interpretation of the full-scale in situ heating test conducted on Callovo-Oxfordian (COx) claystone in the Meuse / Haute-Marne URL simulating a heat-emitting, high-level radioactive waste disposal concept. The test is fully instrumented, and attention is focused on the near-field region's the THM behaviour consisting of the sleeve surrounding the heater and the host rock. The interpretation of the test is assisted by the performance of a coupled numerical analysis based on a coupled formulation incorporating the relevant THM phenomena. The calculations have used a reference isothermal constitutive model especially developed for this type of material. The reference model later has been extended to non-isothermal condition by incorporating thermal dependency of strength parameters and stiffness. The thermomechanical model has been successfully used in the simulation of triaxial tests on COx claystone. The numerical analysis performed has proved able to represent the progress of the experiment very satisfactorily. The performance and analysis of the in-situ test has significantly enhanced the understanding of a complex THM problem and have proved the capability of the numerical formulation and non-isothermal constitutive model to provide adequate predictive capacity. Las rocas argiláceas (arcillas sedimentarias rígidas) proporcionan el trasfondo geológico de muchos proyectos de ingeniería civil. En los últimos años, ha aumentado el interés por este tipo de materiales, porque están siendo considerados como posibles medios geológicos hospedadores de depósitos subterráneos de desechos radiactivos de alta actividad (HLW). El posible uso de este tipo de arcilla como hospedante geológico de residuos radiactivos ha impulsado la construcción de varios laboratorios subterráneos. Entre los muy diferentes temas que se abordan en los Laboratorios de Investigación Subterránea (URL), el comportamiento termo-hidromecánico (THM) de la roca huésped es el que más preocupa a la presente investigación. Las observaciones in situ han revelado un número considerable de procesos THM acoplados en el funcionamiento de un depósito de HLW. En este contexto, el objetivo principal del presente estudio es describir el rendimiento, las observaciones y la interpretación de la prueba de calentamiento in situ a gran escala realizada en piedra arcillosa Callovo-Oxfordian (COx) en la URL de Mosa / Haute-Marne simulando un calor- concepto de eliminación de desechos radiactivos de alto nivel emisor. La prueba está totalmente instrumentada y la atención se centra en el comportamiento del THM de la región de campo cercano que consiste en la manga que rodea el calentador y la roca anfitriona. La interpretación de la prueba es asistida por la realización de un análisis numérico acoplado basado en una formulación acoplada que incorpora los fenómenos de THM relevantes. Los cálculos han utilizado un modelo constitutivo isotérmico de referencia especialmente desarrollado para este tipo de material. Posteriormente, el modelo de referencia se ha ampliado a condiciones no isotérmicas incorporando la dependencia térmica de los parámetros de resistencia y rigidez. El modelo termomecánico se ha utilizado con éxito en la simulación de ensayos triaxiales en arcillas COx. El análisis numérico realizado ha demostrado ser capaz de representar de forma muy satisfactoria el avance del experimento. El rendimiento y el análisis de la prueba in situ ha mejorado significativamente la comprensión de un problema THM complejo y ha demostrado la capacidad de la

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A thermomechanical model for argillaceous hard soils - weak rocks: application to THM simulation of deep excavations in claystone

Cited by 2 publications

References 46 publications

Thermo-hydro-mechanical analysis of Bentonite at residual state

Thermo-hydro-mechanical analysis of Bentonite at residual state

THM analysis of argillaceous rocks with application to nuclear waste underground storage

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