Underpinning is a very common and frequently used method of foundation support where existing foundations are undercut by new constructions (i.e. tunnels or excavation pits). Traditionally, the new and deeper foundations are constructed in small sections below the existing foundation and subsequently linked together. Newer methods involve injection methods or jet grouting to create a new foundation body immediately below the existing foundation. Cement, water or chemicals are combined with the underlying soil particles to form a rigid body, stable enough to bear foundation loads.