Soil description, identification and classification

Unlike other civil engineering and building materials, soils (and rocks) pre-exist on the site of the works, and the first phase of any geotechnical study is to define the nature and condition of these soils. The techniques used to characterize a site's soils are described in two articles of this treatise: "Drilling and boreholes" ([C 228 ]) , and the present article devoted to the description, identification and classification of soils, which presents soil characterization techniques in the laboratory.

Soils taken from boreholes or excavations can be described in several complementary ways: according to the nature, according to the proportions and according to the physical properties of their constituents. The corresponding parameters will be used in the other articles of this treatise devoted to the mechanical properties of soils and structures. The classification, for its part, allows us to convey in a few words an overall picture of each soil, very useful for exchanges between specialists.