Thermo-hydro-mechanical codes

Abstract The Canadian Nuclear Safety Commission (CNSC) used the finite element code FRACON to perform blind predictions of the FEBEX heater experiment. The FRACON code numerically solves the extended equations of Biot s poro-elasticity. The rock was assumed to be linearly elastic, however, the poro-elastic coefficients of variably saturated bentonite were expressed as functions of net stress and void ratio using the state surface equation obtained from suction-controlled oedometer tests. In this paper, we will summarize our approach and predictive results for the Thermo-Hydro-Mechanical response of the bentonite. It is shown that the model correctly predicts drying of the bentonite near the heaters and re-saturation near the rock interface. The evolution of temperature and the heater thermal output were reasonably well predicted by the model. The trends in the total stresses developed in the bentonite were also correctly predicted, however the absolute values were underestimated probably due to the neglect of pore pressure build-up in the rock mass. 

Ohnishi, Y., Shibata, H. and Kobayashi, A. 1987. Development of finite element code for the analysis of coupled thermo-hydro-mechanical behavior of a saturated-unsaturated medium. In Tsang, C.-F. editor. Coupled processes associated with nuclear waste repositories. Academic lYess, Orlando, pp.551-557. 

Tijani, S.M. 1996. Short description of VIPLEF code. Coupled thermo-hydro-mechanical processes of fractured media. Developments in Geotechnical Engineering, 79 507 - 511. 

Chan, T. Guvanasen, V. and Stanchell, F.W. 2003. Verification and validation of a three-dimensional finite-element code for coupled Thermo-Hydro-Mechanical and Salinity (T-H-M-C) modelling in fractured rock mass. This conference. 

Our activities on development of the coupled T-H-M-C code and further demonstration analysis are presented by Neyama et al. in GeoProc 2003 conference, entitled Prototype Code Development for Numerical Experiments on the Coupled Thermo-Hydro-Mechanical and Chemical Processes in the Near-field of a High-level Radioactive Waste Repository . The prototype code is based on the coupled T-H-M code, mass transport code and geochemical code which have been well verified and validated through benchmark tests and various experiments, and... 

PROTOTYPE CODE DEVELOPMENT FOR NUMERICAL EXPERIMENTS ON THE COUPLED THERMO-HYDRO-MECHANICAL AND CHEMICAL PROCESSES IN THE NEAR-FIELD OF A HIGH-LEVEL RADIOACTIVE WASTE REPOSITORY... 

Ohnishi, Y., Shibata, H. Kobayashi, A. 1985. Development of Finite Element Code for the Analysis of Coupled Thermo-Hydro-Mechanical Behaviors of a Saturated-Unsaturated Medium. Proc. Int. Symp. on Coupled Process Affecting the Preformance of a Nuclear Waste Repository. Berkeley pp.263-268. 

VERIFICATION AND VALIDATION OF A THREE-DIMENSIONAL FINITE-ELEMENT CODE FOR COUPLED THERMO-HYDRO-MECHANICAL AND SAUNITY (T-H-M-C) MODELLING IN FRACTURED ROCK MASSES... 

Abstract motif is a three-dimensional finite-element code developed to simulate groundwater flow, heat transfer and solute transport in deformable fractured porous media. The code has been subjected to an extensive verification and updating programme since the onset of its development. In this paper, additional verification and validation works with an emphasis on thermo-hydro-mechanical processes are presented. The verification results are based on cases designed to verify thermo-hydro-mechanical coupling terms, and isothermal and non-isothermal consolidations. A number of validation case studies have been conducted on the code. Example results are repotted in this paper. 

The six verification tests presented in this paper, along with other verification tests presented in the cited literature, have established the ability of the MOTIF finite-element code to accurately solve the equations of groundwater flow, solute and heat transport, and coupled thermo-hydro-mechanical phenomena in porous media, or in fractured media that can be adequately characterized by equivalent porous media (EPM) elements or a combination of EPM and discrete fracture elements. 

The numerical code used is the finite element program CODE BRlGHT. It is based on a mathematical formulation that combines an already existent thermo-hydro-mechanical formulation (Olivella et al., 1995) with the reactive transport equations in a fully coupled way (Guimaraes, 2002). 

Chavant C, Charles P., Duforestel T, Voldoire F., 1999, Thermo-hydro-mechanics of unsaturated porous media in code Aster, technical note, EDF R D, HI-74/99/011/A. 

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