DECOVALEX
DEvelopment of COupled models and their VALidation against EXperiments
The DECOVALEX project is an international research and model comparison collaboration, initiated in 1992, for advancing the understanding and modeling of coupled thermo-hydro-mechanical-chemical (THMC) processes in geological systems. Prediction of these coupled effects is an essential part of the performance and safety assessment of geologic disposal systems for radioactive waste and spent nuclear fuel, and also for a range of sub-surface engineering activities. The project has been conducted by research teams supported by a large number of radioactive-waste-management organizations and regulatory authorities. Research teams work collaboratively on selected modeling cases, followed by comparative assessment of model results. This work has yielded in-depth knowledge of coupled THM and THMC processes associated with nuclear waste repositories and wider geo-engineering applications, as well as the suitability of numerical simulation models for quantitative analysis. Approximately 6 monthly workshops are held internally for whole project, including a public symposium at the end of each phase.
DECOVALEX-2027 is the current and 9th project phase and runs from 2024 through 2027. Modeling teams from 18 international partner organizations participate in the comparative evaluation of seven modeling tasks involving complex field and/or laboratory experiments in the UK, Switzerland, Japan, France and Sweden. Together, these tasks address a wide range of relevant issues related to engineered and natural system behavior in argillaceous and crystalline host rocks.
This task focuses on the development and collaborative testing of new constitutive models for the long-term deformation/damage behaviour of argillaceous rocks. New models developed from microscopic observations and laboratory experiments are then applied to simulate gas injection tests performed on Opalinus Clay (OPA) in the laboratory and at the Mont Terri underground research facility.
The Sandwich experiment in Mont Terri includes a new Sandwich sealing system for repository shafts, which consists of sealing segments (DS) of bentonite and equipotential segments (ES) that are characterized by a higher hydraulic conductivity. The task will perform comparative modelling of the two experimental shafts and supporting laboratory data.
The Fractured Rock Extrapolation, Suitability Criteria and Inflow Prediction (FRESCIP) Task is aimed to develop and test alternative modeling concepts/methodologies such as discrete fracture network (DFN) and channel network models (CNM), with a particular emphasis on conditional simulation based on the types of data that can realistically be expected at successive stages of repository construction.
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences
