Introduction

Abstract

In general, many solids show an internal structure. On the one hand, this is due to the fact that several solids consist of different solid components, such as dense concrete without pores. On the other hand, solids can contain closed and open pores, such as ceramics and soils, as well as concrete. In the past, these materials were, in general, treated as one-component materials lacking an internal structure. Using such a model — one which consists of an ideal material classical continuum mechanics has been very successful. All defined mechanical terms (for example, stress) are thereby understood as average quantities. Classical continuum mechanics can therefore not answer questions concerning the change of pores and the different motions belonging to the phases of liquid-saturated porous solids.