Modeling coupled THM processes of geological porous media with multiphase flow: Theory and validation against laboratory and field scale experiments
2009 (English)In: Computers and geotechnics, ISSN 0266-352X, Vol. 36, no 8, 1308-1329 p.Article in journal (Refereed) Published
A FEM model for analysis of fully coupled multiphase flow, thermal transport and stress/deformation in geological porous media was developed based on the momentum, mass and energy conservation laws of the continuum mechanics and the averaging approach of the mixture theory over a three phase (solid-liquid-gas) system. Six processes (i.e. stress-strain, water flow, gas flow, vapor flow, heat transport and porosity evolution processes) and their coupling effects are considered, which not only makes the problem well-defined, but renders the governing PDEs closed, complete. compact and compatible. Displacements, pore water pressure, pore gas pressure, pore vapor pressure, temperature and porosity are selected as basic unknowns. The physical phenomena such as phase transition, gas solubility in liquid, thermo-osmosis, moisture transfer and moisture swelling are modeled. As a result, the relative humidity and other related variables in porous media can be evaluated on a sounder physical basis. A three dimensional computer code, THYME3D, was developed, with eight degrees of freedom at each node. The laboratory CEA Mock-up test and the field scale FEBEX benchmark test on bentonite performance assessment for underground nuclear waste repositories were used to validate the numerical model and the software. The coupled THM behaviors of the bentonite barriers were satisfactorily simulated, and the effects and impacts of the governing equations, constitutive relations and property parameters on the coupled THM processes were understood in terms of more straightforward interpretation of physical processes at microscopic scale of the porous media. The work developed enables further in-depth research on fully coupled THM or THMC processes in porous media.
Place, publisher, year, edition, pages
2009. Vol. 36, no 8, 1308-1329 p.
THM coupling, Multiphase flow, Porous medium, Bentonite, Relative humidity, Phase transition, Moisture swelling, Thermo-osmosis, Numerical modeling, Code validation
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-32159DOI: 10.1016/j.compgeo.2009.06.001ISI: 000271136500006ScopusID: 2-s2.0-70349459753OAI: oai:DiVA.org:kth-32159DiVA: diva2:409411
QC 201104082011-04-082011-04-072011-04-08Bibliographically approved