Modeling and computing have become an essential part of the analysis and design of engineering systems. This is also becoming the case for ‘Geotechnical systems’ such as foundations, earth dams, tunnels, retaining walls and other soil-structure systems. In Figure 1.1, there are a few examples of such systems.
Soils consist of the assemblage of small particles of mineral matter, usually disintegrated particles derived from rock deposits. The uniqueness of soils relative to other civil engineering materials is that they are naturally formed from geologic processes and they are a composite material, made up of solid mineral matter, water, and sometimes air.
Soils consist of solid particles, enclosing voids or pores. The voids may be filled with air or water or both. These three soil states (or phases) can be visualized by the enlargement of three small samples of soil.