Coupled THMC Simulator Incorporating Pressure Solution with Dual Porosity Model and Its Application to Long-term Flow Simulation of Fractured Rocks

Abstract

We improved our coupled thermo-hydro-mechanical-chemical (THMC) simulator by adopting the dual porosity model to predict the long-term permeability change of the fractured rocks. The model evaluates influence of the geochemical reaction on the evolution of the permeability in fractured rock. Pressure solution that may occur both at grain contacts and the contacting asperities within fractures was incorporated in the model. By using the developed THMC numerical model, long-term prediction of rock permeability under simulated subsurface environments near the radioactive waste repository was conducted. As a result of analysis, the permeability decreased by two orders of magnitude smaller than the initial value due to the pressure solution contacting asperities within fractures in the excavation distributed zone (EDZ). When carrying out radioactive waste disposal, the pressure solution within the fractures may have the effect on minimizing the increasing of the permeability in EDZ area.