GEOMETRICAL EVOLUTION OF STRESSED AND CURVED SOLID-FLUID PHASE BOUNDARIES .1. TRANSFORMATION KINETICS

This contribution is concerned with the fundamental thermodynamic aspe cts of solid-fluid phase transformations in stressed rocks, specifical ly in the context of pressure solution. We concentrate in particular o n the formulation of a kinetic law governing the migration of stressed and curved solid-fluid phase boundaries, an objective that is achieve d by using the methods of the thermodynamics of irreversible processes . We then apply our result to the study of the geometrical evolution o f a fluid-filled cylindrical pore embedded in an isotropic, linear ela stic solid that is subject to a hydrostatic remote stress, assuming th at the interface kinetics controls the phase boundary migration and al lowing for the effects of capillarity. On the basis of this investigat ion, we obtain an analytical expression for the pore's growth and show that phase equilibrium along the cylindrical solid-fluid phase bounda ry is possible only when the pore pressure exceeds a critical value. T he phase equilibrium is found to be kinetically unstable: when subject ed to a small perturbation of its radius, the pore will either grow or shrink. The nature of this instability is further explored in the com panion paper.