The origin of well foundations credits back to prehistoric Indian engineering. The use of well foundations in India hits back to hundreds of years ago for providing deep foundation beneath the water level for monuments, bridges and aqueducts. Most promising example can be use of well foundation in Taj Mahal.
The well foundation is nearly identical to open caissons. Basically well foundation may be constructed on the dry bed or after forming/making a sand island. Most effective use of well foundations is at locations where the depth of water is higher than 4 m to 6 m as well as the water velocity is relatively higher. The wells can be fabricated on the bank of river and then allowed to float to the final required position and then grounded. Proper care and greater accuracy is required to be exercised while grounding the well to make sure that its position is set prefect. After the well has touched the bed, sand bags are then laid/deposited around it for prevention against scours. Generally, well is sunk into the river by 40 60 cm under the influence of its own weight. Further sinking is done by excavating the dredge holes to required level.
Necessary parts or components of well foundations;
- Strong cutting edges: used for sinking mechanism.
- Well curb: the papered section of the well above cutting edge.
- Steining: walls of the well made up of brick masonry, stone masonry and plain or reinforced concrete. It has is constructed proficiently to withstand imposed loads. Additionally it has to be weighty enough for overcoming the frictional resistance while sinking.
Finally when the well has been sunk to the required final depth then the bottom plug is constructed by concreting. This bottom plug work as the base of well is filled partially or totally filled with sand. To the top of well, a top plug is constructed by concreting. Lastly at the top portion a RCC well cap is constructed for transmitting the loading of super structure to the well.