ABSTRACT

The validity of the effective stress principle for saturated soils has been adequately verified by the work of many researchers. The effective stress principle is considered the most significant principle in soil mechanics. The soil particles and contractile skin are assumed to behave as solids in an unsaturated soil. It is assumed that these phases come to equilibrium under applied stress gradient. The equilibrium equation for the water phase, air phase and contractile skin can be written independently. Soil is a multiphase body consisting of the soil skeleton and pore fluid. The distribution of both the soil skeleton and pore fluid is discontinuous; hence soil is not a continuous medium. Representative Elementary Volume (REV) has significant meaning for the definition of physical mechanical quantities and the investigation of the continuity of the quantities. However, it is usually unnecessary to define the size of the REV. The chapter also presents an overview of the key concepts discussed in this book.