Numerical Prediction of the Large-Scale in Situ PRACLAY Heater Test in the Boom Clay

Chen, Guangjing; Dizier, Arnaud; Li, Xiangling; Verstricht, Jan; Sillen, X.; Levasseur, Séverine

doi:10.1007/s00603-021-02405-2

Cited by 16 publications

(5 citation statements)

References 37 publications

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“…Two different types of cement-based materials have been used in this study: samples from the gallery lining and samples from the supercontainer. The lining was made from high strength concrete (28-day compressive strength of 88 MPa [24]). The samples from the lining have been drilled from wedge blocks, which were leftovers from the installation of the connecting gallery, stored at ESV EURIDICE (a European Underground Research Infrastructure for DIsposal of nuclear waste in Clay Environment, located in Mol, Belgium).…”

Section: Methodsmentioning

confidence: 99%

Diffusive Transport of Dissolved Gases in Potential Concretes for Nuclear Waste Disposal

et al. 2021

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In many countries, the preferred option for the long-term management of high- and intermediate level radioactive waste and spent fuel is final disposal in a geological repository. In this geological repository, the generation of gas will be unavoidable. In order to make a correct balance between gas generation and dissipation by diffusion, knowledge of the diffusion coefficients of gases in the host rock and the engineered barriers is essential. Currently, diffusion coefficients for the Boom Clay, a potential Belgian host rock, are available, but the diffusion coefficients for gases in the engineered concrete barriers are still lacking. Therefore, diffusion experiments with dissolved gases were performed on two concrete-based barrier materials considered in the current Belgian disposal concept, by using the double through-diffusion technique for dissolved gases, which was developed in 2008 by SCK CEN. Diffusion measurements were performed with four gases including helium, neon, methane and ethane. Information on the microstructure of the materials (e.g., pore size distribution) was obtained by combining N2-adsorption, mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and water sorptivity measurements. A comparison was made with data obtained from cement-based samples (intact and degraded), and the validity of existing predictive models was investigated.

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Section: Methodsmentioning

confidence: 99%

Diffusive Transport of Dissolved Gases in Potential Concretes for Nuclear Waste Disposal

et al. 2021

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“…[Fig. 1] For deep geological disposal, performance assessment of the host formation focused on isolating the HLW from the biosphere requires that in-situ experiments are complemented by numerical simulations to allow predictions of THM behaviour for extended periods of time (Armand et al, 2017;Chen et al, 2011aChen et al, , 2021De-Bruyn and Labat, 2002;Dizier et al, 2021;François et al, 2009;Selvadurai and Nguyen, 1997), or to allow investigating the effect of host rock degradation due to excavation (Nguyen et al, 2009;Pan et al, 2009;Perras and Diederichs, 2016;Rutqvist et al, 2009a). Mathematical models for such coupled geomechanical systems are often characterized by high dimensionality in which the associated computational cost becomes critical when dealing with inverse problems.…”

Section: Fundingmentioning

confidence: 99%

Using Reduced Basis Approximation for Efficient Surrogate-Based Inverse Identification of Thermo-Hydro-Mechanical Parameters from an In Situ Heating Test

et al. 2022

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In this paper, a reduced order model built from the reduced basis (RB) method is used as a surrogate for an inverse identification problem related to coupled thermo-hydro-mechanical (THM) processes. The RB space -spanned by solutions of the governing THM equations -is constructed using a greedy adaptive procedure guided by an a-posteriori error estimator that selects the optimal snapshot points in a given parametric space. The RB model is assessed in terms of accuracy and computational cost reduction for the three-dimensional transient coupled problem described by the ATLAS III small scale in-situ heating test. The substantial system size reduction and the associated significant computational gain result in a surrogate model suitable for parameter identification procedures in the Boom Clay material. The effectiveness of the proposed strategy is demonstrated by performing inverse analysis based on direct-search and genetic algorithm (GA) optimization supported by real sensor measurement data where 800 times faster computational speed-up was achieved.

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“…For overconsolidated geomaterials like claystone, most of the studies conclude that the volume increase under thermal loading is more pronounced due to the expansion of mineral particles and adsorbed water, while thermal contraction decreases with increases in overconsolidation ratio (Cui et al, 2000;Romero et al, 2005). The in-situ stress level of claystone is lower than its preconsolidation pressure, then an internal frictional model combined with thermoelasticity is usually used (Chen et al, 2021;Tourchi et al, 2021). The yield surfaces for friction model are described by Mohr-Coulomb criterion, where the linearity is valid both in the Coulomb plane and the (p,q) plane.…”

Section: Introductionmentioning

confidence: 99%

Thermal Impact on the Excavation Damage Zone Around a Supported Drift Using the 2nd Gradient Model

2023

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The temperature increase induced by radioactive waste decay generates the thermal pressurisation around the excavation damage zone (EDZ), and the excess pore pressure could induce fracture re-opening and propagation. Shear strain localisation in band mode leading to the onset of micro/macro cracks can be always evidenced before the fracturing process from the lab experiments using advanced experimental devices, hence the thermal effects on the rock behaviour around the EDZ could be modelled with the consideration of development of shear bands. A coupled local 2 nd gradient model with regularisation technique is implemented, considering the thermo-hydro-mechanical (THM) couplings in order to well reproduce the shear bands. Furthermore, the thermo-poroelasticity framework is summarized to validate the implemented model. The discrepancy of thermal dilation coefficient between solid and fluid phases is proved to be the significant parameter leading to the excess pore pressure. Finally, an application of a heating test based on Eurad Hitec benchmark exercise with a drift supported by a liner is studied. The strain localisation induced by thermal effects is properly reproduced. The plasticity and shear bands evolutions are highlighted during the heating, and the shear bands are preferential to develop in the minor horizontal principal stress direction. Different shear band patterns are obtained with changing gap values between the drift wall and the liner. A smaller gap between the wall and the liner can limit the development of shear bands.

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Numerical Prediction of the Large-Scale in Situ PRACLAY Heater Test in the Boom Clay

Cited by 16 publications

References 37 publications

Diffusive Transport of Dissolved Gases in Potential Concretes for Nuclear Waste Disposal

Diffusive Transport of Dissolved Gases in Potential Concretes for Nuclear Waste Disposal

Using Reduced Basis Approximation for Efficient Surrogate-Based Inverse Identification of Thermo-Hydro-Mechanical Parameters from an In Situ Heating Test

Thermal Impact on the Excavation Damage Zone Around a Supported Drift Using the 2nd Gradient Model

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