This document discusses foundations in lake and river beds. It begins by introducing foundations and their purpose of distributing structural loads to the ground. There are two main types of foundations: shallow and deep. In lakes, soft sediments require careful attention as clay can cause issues. Common lake foundations are pile, floating, and buoyant foundations. River beds present challenges from erosion. Common river bed foundations include spread footing, stepped, pile, well, pier, and caisson foundations. Caissons can be floated into place and sunk, making them suitable for rivers. Pile foundations are used when scouring is a risk. Foundation selection depends on factors like soil type and water velocity.

1. FOUNDATION IN LAKE AND
RIVER BEDS
Submitted by:
Saurav Poudel
Roll No: 11
Second Semester,
Engineering Geology
Submitted to:
Central Department
of Geology, Kirtipur

2. INTRODUCTION
 A foundation is the element of a structure which connects it to the
ground, transferring loads from the structure to the ground.
It directly contacts the soil and transfers the superstructure's load to
it.
Is required for distributing the loads of the superstructure on a large
area

3. TYPES OF FOUNDATION
In general, there are two types of foundations:
Shallow Foundation
According to Terzaghi, a foundation is shallow if its depth is equal to
or less than its width(D‹B).
Normally shallow foundation used upto 5m depth.
Deep Foundation
The depth of foundation is very large in comparison to its width
(D›B).

4. PURPOSES OF A FOUNDATION
To distribute the weight of the structure over a large area in order to
avoid overloading the underlying soil.
To anchor the structure against natural forces including earthquakes,
floods, droughts, frost heaves, tornadoes and wind.
To ensure a flat, firm bed for construction activities
To improve the structure's overall stability.

5. FOUNDATION IN LAKE
The lake is typically filled with soft sediments with a lot of
moisture.
Building in these locations requires careful attention because
clay is always a problem when it comes to foundation
engineering.
The soil bearing capacity is one of the most crucial elements
that determines the optimum type of foundation for a lake.
Based on the soil bearing pressure, the choice of shallow or
deep foundation can be determined.

6. TYPES OF FOUNDATIONS USED IN
LAKES
There are generally three common types of foundation used in
lakes:
1. Pile Foundation
2. Floating Foundation
3. Buoyant Foundation

7. PILE FOUNDATION
• The term ‘pile foundation’ denotes a
construction for the foundation of wall or
pier which is supported on piles.
• It is used for stratum of required bearing
capacity is at greater depth.
• A Pile foundation can help reach greater
depth to allow greater bearing capacity in
soft ground conditions.
Fig: pile foundation

8. FLOATING FOUNDATION
Fig: A floating foundation
Usually constructed by excavating the
ground so that the weight of the
structure being built on it equals the
total weight of the soil that was
removed from the earth, including the
weight of the water that was present in
the soil before the construction of the
structure.

9. BUOYANT FOUNDATION
• An existing structure is modified with a
buoyant foundation, a form of
amphibious foundation, to enable it to
float as high as required during floods
while remaining on the ground during
normal conditions.
• A solution to elevated housing is buoyant
foundations, which allow homes to stay
on the ground in normal conditions but
rise as far as necessary when water is
ponded and rises. Fig: Buoyant Foundation

10. FOUNDATION IN RIVER BEDS
The river is the most significant erosive agent that can change
the conditions of the land or river beds.
It would be highly expensive to build bridges or any other
structures across the entire natural spread of alluvial rivers in
flood plains since they spread out over such a huge region
during floods.
To flow axially via the diversion construction, its path must be
narrowed and restricted.

11. TYPES OF FOUNDATION IN RIVER
BEDS
1. Spread footing foundation
2. Benching or Stepped Foundation
3. Pile Foundation
4. Well Foundation
5. Pier Foundation
6. Caisson’s Foundation

12. SPREAD FOOTING FOUNDATION
On typical alluvial soil types, this style
of foundation can often support three to
four-story buildings.
The spread footing is composed of
several footings below ground level and
a base of concrete, typically lime
concrete.
The bearing capacity of the soil and the
magnitude of the load determine the
depth and width of the foundation.
Fig: Spread footing types

13. BENCHING OR STEPPED
FOUNDATION
This type of foundation is
provided on high gradient
river beds or in those
situations where the ground is
sloppy.
In these foundations, the
excavation trenches are made
in the form of steps.
All the steps should be
preferable of equal length and
depth.
Fig: Stepped Foundation

14. PILE FOUNDATION
Piles are used when,
Spreading foundations is not cost-
effective and there is deeper hard soil.
Building raft or grillage foundations would
be exceedingly expensive.
The foundations are required to support
significant concentrated loads.
There is a chance that irrigation canals
will be built nearby.
Scouring is concentrated more on the
riverbed for bridges, it is often effective.
Fig: Pile Foundation in river bed

15. WELL FOUNDATION
In deep sandy and soft solid
soil, wells are a practical way
to lay a stable foundation. Well,
the foundation is typically
offered.
As with building a bridge pier,
a temporary dam is built to
keep water away from the
construction site when building
a well foundation in flowing
water.
Fig: Well Foundation

16. PIER FOUNDATION
The types of pier foundations are masonry or
concrete piers and drilled caissons.
Pier is inserted down to the bedrock.
Pier is typically dug out and cast in place using
forms.
This method is easy and requires less amount of
materials and labor. The materials required here
is easily available
Figure: Pier foundation with arches.

17. Caisson Foundation
 Caissons are carried to a hard stratum, such
as compact sand, gravel hard clay, or rocks.
 When the depth of the water is significant
and the velocity of the water is such that a
cofferdam cannot be built quickly and
affordably, caissons are constructed.
 A caisson is a steel box with two walls that
is watertight and has cutting edges attached
to its bottom.
 They do consist of piles but are generally
shorter.
Fig: Caisson Foundation

18. TYPES OF CASSIONS
Box Caissons
Open Caissons
Pneumatic Caissons
Excavated Caissons
Floating Caissons
Compressed Air Caissons
Monolithic Caissons

19. Conclusion
• Generally dam is a structure built across a stream, a river, or an estuary to
retain water.
• Cofferdams are commonly used for construction or repair of permanent
dams, oil platforms, bridge piers, etc., built within water.
• The choice of bridge foundation depend upon the importance of bridge, size,
nature of soil and sub soil in the bed and velocity of water flow.
• The reason for choosing the caisson is that it can be floated to the desired
location and then sunk into place.
• Pile foundation is done when structure are located on river bed and
foundation are likely to be scoured due to action of water.

20. THANK YOU