ABSTRACT
The beginning reader will quickly realize that soils are unusual engineering materials, mainly if compared with materials described in structural mechanics. The reason is that soils are natural materials, formed by the weathering of rocks, and the behaviour of soils is a legacy of natural processes, from their origin to the actual state. This gives soils a character of inhomogeneity and anisotropy, and basic parameters, such as strength, stiffness and hydraulic conductivity, need to be measured instead of being specified and may vary over a wide range.
