Coupled thermo-hydro-mechanical analysis of engineered barriers for high level radioactive waste

Abstract

A general formulation for the performance of coupled thermo-hydro-mechanical (THM) analysis is presented. A multi-phase and multi-species approach has been adopted for the development of the formulation. The analysis considers a porous material with three phases (solid, liquid and gas) and three species (mineral, water and air). The formulation is presented in terms of governing equations, constitutive laws and equilibrium restrictions. An extensive programme of coupled THM analyses simulating the behaviour of the near field in a scheme for the underground disposal of high level radioactive waste is presented. The analyses are able to take into account the main interactions between the various processes that occur in the engineered barrier and immediately adjacent rock associated with heating and hydration phenomena. Examination of the results leads to a series of significant conclusions concerning the thermal, hydraulic and mechanical aspects of the problem