2026-04-14T03:02:33Zhttps://recercat.cat/oai/request

oai:recercat.cat:2117/4222972026-01-18T08:24:28Zcom_2072_1033col_2072_452950

urn:hdl:2117/422297 Fully coupled THM constitutive model for clay rocks: formulation and application to laboratory tests Song, Fei Gens Solé, Antonio Collico, Stefano Grgic, Dragan Wang, Huaning Àrees temàtiques de la UPC::Enginyeria civil::Geotècnia::Mecànica de roques Hard soil Soft rocks Unsaturated/saturated conditions THM coupling processes Thermal pressurization Constitutive model This study presents a fully coupled thermo-hydro-mechanical (THM) constitutive model for clay rocks. The model is formulated within the elastic-viscoplasticity framework, which considers nonlinearity and softening after peak strength, anisotropy of stiffness and strength, as well as permeability variation due to damage. In addition, the mechanical properties are coupled with thermal phenomena and accumulated plastic strains. The adopted nonlocal and viscoplastic approaches enhance numerical efficiency and provide the possibility to simulate localization phenomena. The model is validated against experimental data from laboratory tests conducted on Callovo-Oxfordian (COx) claystone samples that are initially unsaturated and under suction. The tests include a thermal phase where the COx specimens are subjected to different temperature increases. A good agreement with experimental data is obtained. In addition, parametric analyses are carried out to investigate the influence of the hydraulic boundary conditions (B.C.) and post-failure behavior models on the THM behavior evolution. It is shown that different drainage conditions affect the thermally induced pore pressures that, in turn, influence the onset of softening. The constitutive model presented constitutes a promising approach for simulating the most important features of the THM behavior of clay rocks. It is a tool with a high potential for application to several relevant case studies, such as thermal fracturing analysis of nuclear waste disposal systems. This work was funded by the European Union's Horizon 2020 research and innovation programme under a grant agreement (Grant No. 847593), partially supported by the Fundamental Research Funds for the Central Universities (Grant No. 22120240029). The authors thank the organizing Committee of Unsat-Waste2023 for their invitation to contribute to the special issue “Unsat-Waste2023". Peer Reviewed Postprint (published version) 2025-04 Article https://www.sciencedirect.com/science/article/pii/S1674775524003196 info:eu-repo/grantAgreement/EC/H2020/847593/EU/European Joint Programme on Radioactive Waste Management/EURAD http://creativecommons.org/licenses/by/4.0/ Open Access Attribution 4.0 International Science Press