The phenomena of rock dissolution in the subsoil can be natural or anthropogenic and can be accentuated by current climate change. Both rock boundaries surface and rock pore dissolution introduce an additional disturbance into a geomechanical problem, with significant consequences for the mechanical response of the medium, in particular in terms of subsidence, localised or generalised collapse, loss of stability, etc. The dissolution of rock matrix or rock discontinuities (fractures) modifies not only the field of stresses but also the hydraulic features of the surrounding environment and the mechanical properties of the rock. Numerical modelling of transient dissolution phenomena, for rocks such as salt and gypsum, is approached by assuming a diffuse physical interface of finite thickness between the fluid and the solid material. The diffuse interface model is based on a change of scale from a pore-scale or micro-scale dissolution problem up to a macro-scale description. A process that involves various hypotheses which are carefully reviewed. With the help of numerous 2D and 3D numerical simulations of a variety of boundary value problems, we demonstrate the strength and robustness of such an approach, in particular at large spatial scales such as those found in geomechanics. We also highlight the current shortcomings of this method and the possible improvements that can be achieved.