Lawrence Berkeley National Laboratory

An overview is given of recent progress in the understanding, monitoring, and modeling of coupled thermo-hydro-mechanical (THM) processes in geologic systems, in the context of major practical applications. The progress has been made possible through individual research efforts, as well as international cooperative research projects. As an example of international cooperation, the DECOVALEX project is described. Initiated in 1992, the project has progressed successfully through three major stages. It has played a key role in the development of the field of mathematical modeling and testing of coupled THM processes in fractured rocks and buffer/backfill materials, a subject of importance for performance assessment of a radioactive waste geologic repository. The DECOVALEX project has been supported by a large number of radioactive waste management organizations and regulatory authorities, including those in Canada, Finland, France, Japan, Germany, Spain, Sweden, UK, USA, and EU. This paper presents a summary of the project, including the objectives, scope, problems investigated, scientific achievements and major outstanding issues, with emphasis on the science of the coupled THM processes.