In this paper, we present a sensitivity study for the numerical modelling of hydromechanical coupling around a shaft in partially saturated claystone. Two representative constitutive models have been used: an elastoplastic damage model (IDEPLML) and an elastic perfect plastic model based on the Hoek and Brown failure criterion (H&B). A series of comparative studies have been performed with respect to main parameters involved in coupling process (mechanical, hydraulic and hydric properties). The emphasis is put on the evaluation of induced plastic, damaged and failed zone due to excavation and drying process.
Dans ce papier, nous presentons une etude numerique parametrique du comportement hydromecanique couple d'une argilite partiellement sature, lors du creusement et de la maintenance d'un puit L'etude parametrique porte à la fois sur le type de modèle et sur les principaux paramètres (mecaniques hydrauliques et hydriques) intervenant dans le couplage. L'accent est principalement porte sur l'evaluation des zones plastifiees autour de l'ouvrage lors de la desaturation.
In unserem Beitrag geht es um eine digitale parametrische Untersuchung ueber das hydromechanische Verhalten eines teilweise durchtrankten Tons beim Abteufen und dem Betrieb von Schachten. Die parametrische Analyse konzentriert sich auf den Modelltypus und auf die wesentlichen bei der Verbindung wirksamen Parameter, d.h. die mechanischen, hydraulischen und hydrologischen. Der Schwerpunkt liegt auf der Bewahrung der plastifizierten Bereiche des Bauwerkes wahrend der Austrocknung.
In the framework of the underground research laboratory conducted by the French Agence Nationale de la gestion des Dechets Radioactifs (ANDRA), in the eastern region of France, numerical investigations have being performed in order to estimate thermohydromechanical disturbances during expected experiments. This paper presents one part of such investigations, dealing with the prediction of plastic deformation, induced damaged and failure zone due to excavation and drying process around the main vertical shaft. These results are supposed to give a preliminary estimation of expected disturbances and then lead to a better instrumentation procedure during in situ experiments in the shaft. This study is limited to isothermal conditions.
In this section, we present the outlines of two constitutive models used for the description of poromechanical behaviour of partially saturated claystone.
This model if formulated in the framework of plasticity for unsaturated porous media and continuum damage mechanics. The material is assumed to be saturated by a liquid phase (noted by index w) and a gas mixture (noted by index g). The gas mixture is a perfect mixture of dry air (noted by index da) and vapour (noted by index va). Based on experimental data on the claystone, the basic mechanical behaviour can be characterised by a coupled elastoplastic damage. The poroelastic behaviour of unsaturated material is non-linear and depends on the water saturation degree. Further, in partially saturated materials, the plastic compaction and swelling can occur due to an only change of capillary pressure. It should be considered as independent loading force (Alonso et al. 1990).
