Analysis of coupled thermal-hydro-mechanical processes during small scale in situ heater experiment in Callovo-Oxfordian clay rock introducing a failure-index permeability model

To better understand the coupled thermo-hydro-mechanical processes in Callovo-Oxfordian (COx) claystone formations induced by heat emitting high-level radioactive waste, different scales of in-situ heater experiments have been conducted ANDRA Meuse/Haute-Marne Underground Research Laboratory (M/HM URL) at Bure France. In order to prove predictability numerical codes for a site-scale repository, two experiments, small-scale (TED) and full-scale experiment (ALC), intensively investigated teams within international project DECOVALEX 2019. this study, we present results obtained further developing using finite element OpenGeoSys (OGS) simulator with novel approaches. (1) A failure index-dependent permeability model is introduced into THM formulation consider effect changes excavation-damaged zone (EDZ) on pore pressure development during excavation subsequent heating phases, respectively. (2) more general equation state water according International Association Properties Water Steam (IAWPS) taking account vapour behaviour implemented simulate increase high temperature heating. The complete comparison study presented Task E synthesis paper [46].