Foundation (engineering)
A foundation is the element of a structure which connects it to the ground, and transfers loads from the structure to the ground. Foundations are generally considered either shallow or deep. Foundation engineering is the application of soil mechanics and rock mechanics (Geotechnical engineering) in the design of foundation elements of structures.
Deep foundation
Under-reamed piles have mechanically formed enlarged bases that are as much as 6 m in diameter. The form is that of an inverted cone and can only be formed in stable soils. The larger base diameter allows greater bearing capacity than a straight-shaft pile.