Soil mechanics is a branch of
engineering mechanics that describes the behavior of
soils. It differs from fluid mechanics and solid mechanics in the sense that soils consist of a heterogeneous mixture of fluids (usually air and water) and particles (usually
clay,
silt,
sand, and
gravel) but soil may also contain organic solids, liquids, and gasses and other matter. Along with
rock mechanics, soil mechanics provides the theoretical basis for analysis in
geotechnical engineering, a subdiscipline of
civil engineering, and
engineering geology, a subdiscipline of
geology. Soil mechanics is used to analyze the deformations of and flow of fluids within natural and man-made structures that are supported on or made of soil, or structures that are buried in soils. Example applications are building and bridge foundations, retaining walls, dams, and buried pipeline systems. Principles of soil mechanics are also used in related disciplines such as engineering geology,
geophysical engineering,
coastal engineering,
agricultural engineering,
hydrology and
soil physics.