On the Thermo-poro-mechanics of Chemically Active Faults
This chapter summarizes a theory that couples the solid and fluid-like behavior. This theory must be able to provide the framework for modeling both the formation of faults and their postfailure evolution. The chapter shows that the formation and postfailure evolution of faults depend strongly on the coupled multiphysical effects affecting pressure, temperature, and chemical conditions. It highlights the important role of any type of solid-fluid phase transitions that govern the second-degree localization process in the core of the shear zone. Within the framework of the solid mechanical instabilities, the shear zone thickness emerges as a solution, depending on the microstructure. The chapter introduces the Helmholtz free energy, being a function of the elastic strain, temperature and the internal variables. The energy balance equation, together with the second law of thermodynamics and Fourier’s law of diffusion, provides the local form of the entropy production equation.
