Deep repository in geological formations is the preferential solution considered in many countries to manage high-level nuclear wastes. In Switzerland, the Opalinus Clay is a candidate host rock. In this context, in s...Deep repository in geological formations is the preferential solution considered in many countries to manage high-level nuclear wastes. In Switzerland, the Opalinus Clay is a candidate host rock. In this context, in situ and laboratory tests are conducted on Opalinus Clay to demonstrate the feasibility of deep disposal in this argillaceous formation. This paper presents a constitutive model able to fit the experimental data obtained from some triaxial tests conducted by Jahns(2013) on cores from borehole Schlattingen SLA-1. The elasto-plastic behaviour of Opalinus Clay is reproduced thanks to a DruckerPrager model, taking into account the anisotropy behaviour of this sedimentary rock. The objective is to employ a single set of parameters representative of the material. In a second version of the model, the stress-dependence of the elastic properties and damage are taken into account. Finally, the parameters calibrated with experimental tests are used to simulate the excavation of a gallery with a second gradient approach.展开更多
The simulation of rarefied gasflows through complex porous media is chal-lenging due to the tortuousflow pathways inherent to such structures.The Lattice Boltzmann method(LBM)has been identified as a promising avenue ...The simulation of rarefied gasflows through complex porous media is chal-lenging due to the tortuousflow pathways inherent to such structures.The Lattice Boltzmann method(LBM)has been identified as a promising avenue to solveflows through complex geometries due to the simplicity of its scheme and its high parallel computational efficiency.It has been proposed to model the stress-strain relationship with the extended Navier-Stokes equations rather than attempting to directly solve the Boltzmann equation.However,a regularization technique is required tofilter out non-resolved higher-order components with a low-order velocity scheme.Although slip boundary conditions(BCs)have been proposed for the non-regularized multiple relaxation time LBM(MRT-LBM)for planar geometries,previous slip BCs have never been verified extensively with the regularization technique.In this work,following an extensive literature review on the imposition of slip BCs for rarefiedflows with the LBM,it is proven that earlier values for kinetic parameters developed to impose slip BCs are inaccurate for the regularized MRT-LBM and differ between the D2Q9 and D3Q15 schemes.The error was eliminated for planarflows and good agreement be-tween analytical solutions for arrays of cylinders and spheres was found with a wide range of Knudsen numbers.展开更多
文摘Deep repository in geological formations is the preferential solution considered in many countries to manage high-level nuclear wastes. In Switzerland, the Opalinus Clay is a candidate host rock. In this context, in situ and laboratory tests are conducted on Opalinus Clay to demonstrate the feasibility of deep disposal in this argillaceous formation. This paper presents a constitutive model able to fit the experimental data obtained from some triaxial tests conducted by Jahns(2013) on cores from borehole Schlattingen SLA-1. The elasto-plastic behaviour of Opalinus Clay is reproduced thanks to a DruckerPrager model, taking into account the anisotropy behaviour of this sedimentary rock. The objective is to employ a single set of parameters representative of the material. In a second version of the model, the stress-dependence of the elastic properties and damage are taken into account. Finally, the parameters calibrated with experimental tests are used to simulate the excavation of a gallery with a second gradient approach.
基金Financial support from the Simulation-based Engineering Science(Genie Par la Simulation)program funded through the CREATE program from the Natural Sciences and Engineering Research Council of Canada is gratefully acknowledged.
文摘The simulation of rarefied gasflows through complex porous media is chal-lenging due to the tortuousflow pathways inherent to such structures.The Lattice Boltzmann method(LBM)has been identified as a promising avenue to solveflows through complex geometries due to the simplicity of its scheme and its high parallel computational efficiency.It has been proposed to model the stress-strain relationship with the extended Navier-Stokes equations rather than attempting to directly solve the Boltzmann equation.However,a regularization technique is required tofilter out non-resolved higher-order components with a low-order velocity scheme.Although slip boundary conditions(BCs)have been proposed for the non-regularized multiple relaxation time LBM(MRT-LBM)for planar geometries,previous slip BCs have never been verified extensively with the regularization technique.In this work,following an extensive literature review on the imposition of slip BCs for rarefiedflows with the LBM,it is proven that earlier values for kinetic parameters developed to impose slip BCs are inaccurate for the regularized MRT-LBM and differ between the D2Q9 and D3Q15 schemes.The error was eliminated for planarflows and good agreement be-tween analytical solutions for arrays of cylinders and spheres was found with a wide range of Knudsen numbers.
