For structures to be placed within a proposed area, it is necessary to ascertain the bearing capacity of the soil. This is important for reasons of overestimation and underestimation. Subsoil investigation is a very important aspect of engineering which deals mostly with the subsoil on which foundations for structures will be placed.
Deep foundations in the form of piles are used to transmit pressures from a weaker soil (usually at or near the surface) to more competent soil at depth. The Piling works are carried out based on the recommendations supplied, prior to which a subsoil investigation must have been carried out.
The use of geophysical surveys to determine various items such as depth to water, aquifers and area of good yield and depth to buried outcrops and minerals is of importance. Other uses may involve determination of soil profile, depth to a difficult layer or the knowledge of core stone positions, cavities or sink holes.