Geotechnical investigations are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused by subsurface conditions. This type of effort is known as a “site investigation” and also helps measure the thermal resistivity of soils or backfill materials required for underground transmission lines, oil and gas pipelines, radioactive waste disposal and solar thermal storage facilities. Subsurface exploration usually involves soil sampling and laboratory tests of the soil samples retrieved.

Soil boring is an essential step that must be taken before significant constructive work can begin. Boring is a standard technique used to survey soil by taking several shallow cores out of the sediment. As seen in the accompanying photos, it is used when a drilling jacket or jack-up rig is to be supported on the soil itself.