According to Wikipedia, geotechnical engineering, also known as geotechnics, is the branch of civil engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rockmechanics to solve engineering problems and relies on knowledge of geology, hydrology, geophysics, and other related sciences. Geotechnical engineering is used to investigate subsurface conditions and materials, determine the physical and mechanical properties of soil and rock, evaluate natural slopes and man-made earthworks, and design foundations and earth-retaining structures for buildings, bridges, roads, tunnels, dams, and other civil engineering projects.

The field has applications in civil engineering, mining engineering, petroleum engineering, coastal engineering, and offshore construction. Geotechnical engineers also assess and reduce risks associated with landslides, earthquakes, settlement, and slope instability, helping to ensure the safety, stability, and durability of engineering structures.