ABSTRACT
Note that when temperature is introduced to the description of a mechanical process, one obtains a coupling between temperature and deformation through thermal expansion. This coupling causes the propagation of a process that is called second sound in mechanics. When porosity is introduced as a dynamic variable in a porous medium one obtains a coupling between porosity and pressure through fluid flow and elastic deformations of the matrix. The thermomechanical and thermodynamic descriptions of porous media constructed in Chapters II and III describe this coupling. These equations predict a dynamic interaction between porosity and pressure which gives rise to the propagation of four-coupled porosity pressure processes. Two of these processes are the seismic p-waves discussed in Chapter V. The third of these processes (fluid motions causing an increase in porosity and pressure) propagates very near the incompressible limit of fluid motions (~100m/s in water saturated sands) and the fourth diffuses quasi-statically as a porosity pressure diffusion process.
