Physical Mechanics of In-Pore Phase Transition

摘要

In this paper we show how the mechanics of confined phase transition within a deformable porous solid can be addressed in a unique framework, whatever the phase transition considered, either the liquid-gas transition involved in the drying of porous materials or the liquid-solid transition involved in their freezing. Indeed, owing to stability considerations a hydrostatic stress is shown to ultimately prevail within the solid crystal phase so that the latter behaves like a compressible elastic fluid as long as only in-pore phase transition is involved. The extension of saturated poroelasticity to unsaturated conditions allows us to work out appropriate constitutive equations to capture the deformation resulting from in-pore phase transition within an elastic porous solid, while the use of homogenization schemes provides estimates of the unsaturated poroelastic these constitutive equations involve. The prediction of the drying shrinkage or that of the deformation due to cryosuction during freezing reveals the significant effect of the pore size distribution, since the intensity of both the deformation and the elastic energy that the solid matrix can store strongly depends upon the homogenization scheme.