DEEP FOUNDATIONS: Well Foundations (or caissons).

Well foundations or caissons are box like structure-circular or rectangular-which are sunk from the surface of either land or water to the desired depth. They are much large in diameter than the peir foundations or drilled caissons. Caisson foundations are used for major foundation works, such as for:

(i) bridge piers and abutments in rivers, lakes etc,
(ii) Wharves, quay walls, docks.
(iii) Brceak waters and other structures for shore protections.
(iv) Large water front structures such as pump houses, subjected to heavy vertical and horizontal loads.

Well foundations or caissons are hollow from inside, which may be filled with sand, and are plugged at the bottom. The load is transferred though the perimeter wall, called steining (Fig. 2.10).

Well foundations ar not used for buildings.

                                                       FIG. 2.10.  WELL FOUNDATION.