Numerical simulation for influences of pressure solution on thermo-hydro-mechanical coupling in granule aggregate rock

The model of pressure solution for granular aggregates established by Taron et al is introduced into the FEM code for analysis of thermo-hydro-mechanical coupling in porous media developed by the first author. Aiming at a hypothetical model for nuclear waste disposal in an unsaturated quartz aggregate rock mass with a laboratory scale, two computational conditions are designed: (1) the porosity and the permeability of rock mass are functions of the pressure solution; (2) the porosity and the permeability are constants, then the corresponding numerical simulations for a disposal period of 4 years are carried out; and the states of temperatures, solute concentrations in the intergranular fluid film and at the pore space, removal and precipitation masses, porosities and permeabilities, pore pressures, flow velocities and stresses in the rock mass are investigated. The results show: at the end of the calculation in case 1, pressure solution makes the porosities and the permeabilities decrease to about 43%-54% and 4.4% -9.1% of their initial values; under the action of the release heat of nuclear waste, the negative pore pressures in case 1 and case 2 are about 1.0-1.25 and 1.0-1.1 times of the initial values respectively; so the former represents an obvious effect of pressure solution; the magnitudes and distributions of stresses within the rock mass in the two calculation cases are much the same.