This document discusses different types of caisson foundations used in construction, including box caissons, open caissons or wells, and pneumatic caissons. Box caissons are open at the top and closed at the bottom and are built on land then launched, while open caissons or wells are open at both the top and bottom. Pneumatic caissons are open at the bottom and closed at the top, using compressed air to remove water and allow working in a dry environment. Well foundations can take the form of multiple wells or monoliths sunk together, or open cylinders used for bridge pier foundations. Selection depends on factors like depth of water, load requirements, and flow conditions.

1. S.P.B Patel Engineering College
NAME ENROLLMENT NO.
Mayank b dave 136930306521
Chetan k patel 136930306524
Narendrasing vaghela 136930306541
Subject :- Advance construction tech

2. Caissons
Types of
caissons
Pneumatic caissons
(closed at top and
open at bottom)
Box caissons
(open at top and
closed at bottom)
Open cassions or well
(open at top and bottom)
single Multiple Cylinders

3. Box Caissons

4. • A box caisson is a strong water tight vessel open at top
and closed at bottom is made of timer, reinforced concrete
or steel.
• This caisson is built on land, then launched and floated
to pier site where it is sunk in position. Such a type of
caisson is used where bearing stratum is available at
shallow depth, and where loads are not very heavy.

5. Open caissons or Wells

6. An open caisson is a box of timber, reinforced
concrete , steel or masonry which is open at the top
and at the bottom. It is used for building and bridge
foundations. Open caissons are also called well
foundations.

7. Shapes of wells :-

8. Multiple wells or Monoliths :-

9. Multiple Wells
The monoliths well s which are sunk together.
Each individual well has got a separate cutting
edge and dredging in each of the well can be done
Separately.
As the monoliths are of bigger dimension, they
can not be built On the site in the water
The dredging well should be large enough to
permit easy passage of excavating

10. Cylinders :-

11. An open cylinder can be conveniently used of the foundation
of bridge piers. The cylinder is a light shell which invariably
becomes the part of the permanent structure.
Cylinders are used as a foundation when depth of water is
more than 12 m or when it becomes essential to go deep to
avoid exposure of foundations due to scouring action of
flowing water.

12. Disadvantages :-
(1)As the diameter of cylinder is small, it’s load carrying
capacity is less.
(2)There are more chances of lifting of the cylinders.
(3)They require additional for sinking as their self weight is
less.
(4)The thickness is less and hence, the are not suitable for
the high bridges.
(5)When water is flowing with high velocity of flow, it is
difficult to sink the cylinders.

13. Advantages :-
(1) The construction is simple.
(2) The cost is low.
(3)As the diameter of cylinder is small, the obstruction the
water flow is less.
(4)The quantity of excavation is less.
(5)They do not require expensive and complicated lifting
devices.

14. Pneumatic caissons :-

15. A pneumatic caisson is open at bottom and closed at top. This
is useful at locations where it is not possible to adopt wells.
They are suitable when the depth of water is more than 12 m,
and maximum depth of water up to 35 m.
The essential feature of a pneumatic caisson is that
compressed air is used to remove water from the working
chamber at the bottom, and the foundation work is carried out
in dry conditions.
Normally, the tolerable air pressure under which a man can
work is limited to 0.35 N/mm.