1. Introduction

Modules THM deal with the equations of the mechanics of continuous media using the theory of possibly unsaturated porous media and considering that mechanical, thermal and hydraulic phenomena are completely coupled.

Here we present the equilibrium equations, or conservation equations, solved by these modules. We give a definition of generalized constraints and generalized deformations, making it possible to define in a fairly general way what a THM law of behavior is - at least what the modules considered consider as such - and making it possible to treat the nonlinear equations shown in the framework of the algorithms of the operator STAT_NON_LINE.

The THM laws of behavior strictly speaking are not developed in this document, but in document [R7.01.11].

Chemical phenomena (transformations of constituents, reactions producing constituents, etc.), as well as radiological phenomena, are not taken into account. Mechanical, hydraulic and thermal phenomena are taken into account or not depending on the behavior invoked by the user in command STAT_NON_LINE, according to the following nomenclature:

Modeling	Phenomena taken into account
KIT_HM	Mechanics, hydraulics with unknown pressure
KIT_HHM	Mechanics, hydraulics with two unknown pressures
KIT_THH	Thermal, hydraulic with two unknown pressures
KIT_THM	Thermal, mechanical, hydraulic with unknown pressure
KIT_THHM	Thermal, mechanical, hydraulic with two unknown pressures

Some models (see documents [U3.13.08] and [U3.14.07]) of THM are available with regularization by second dilation gradient. For aspects relating to the second gradient of these models, refer to [R5.04.03].