P.BY: 1) Vishal Tembhare 4) Sarojini

Hatwar 2) Shiva kawale 5) Dipali Rane 3) Madhuri Katre 6) Pramod

Harinkhede

SHRI, L. M. COLLEGE OF POLYTECHNIC, AMGOAN

Seminar On :- Foundation

Civil Engineering(3rd sem.)

HOD(C.E.), Guided By, Mr.P.R. Rawte Mr.R.Daseriya

INTRODUCTION

Foundation is the part of structure which receives load of the building and transfers it safely in the lower soil strata without any excessive settlements .

Foundation is the lowest part of structure below the ground level which provides the base for structure or building.

Functions of foundation : 1) To distribute the total load over the larger area.2) To support the structures.3) To increase stability of the structures against various disturbance.4) To prepare a level surface for concreting and masonry work.

TYPES OF FOUNDATIONS

Shallow foundation

Deep foundation

SHALLOW FOUNDATION :- A foundation which have depth is equal to its width or less than width are called as shallow foundation.

1) Wall footing 2) Isolated footings 3) Combined footings 4) Inverted arch footings 5) Cantilever footings 6) Grillage footings 7) Raft or Mat foundations

TYPES OF SHALLOW FOUNDATION

1) Wall footings:- The wall footings are of two varieties i.e. Simple & Stepped. The Simple footing is used under compound wall and light weight structures whereas the stepped footing is used under load bearing structure.

2) Isolated Footings :-

These footings are used to support individual columns. This is most commonly practiced footing.

3) Combined footings:- a) Rectangular footings :- These footings are provided under two columns where the loads on the columns are equal.

b) Trapezoidal footings :- Trapezoidal footings are provided when two columns unequally loaded.

Rectangular footings

4) Inverted arch footings:- It is suitable to be used for the construction of bridges , tanks ,underground sewers, and reservoirs. Such type of footings used where the loads is concentrated over the columns and where it is desired to distribute the load over a large area.

5) Cantilever footings:- This type of footing, is used when a column is near the plot boundary and column footing is not permitted to extend beyond plot boundary.

6) Grillage foundation:- Grillage foundation is used to transmit heavy loads from steel columns to the soil having low bearing capacity. Such foundations are lighter and are found to be economical because it avoids deeper excavations.

7) Raft or Mat foundation:- It is suitable where the ground is soft , clay is marshy having low bearing capacity of soil and subsoil water condition are uncertain.

DEEP FOUNDATION :- A foundation which have depth is greater than its width is known as deep foundation.

1) Pile foundation:- Piles are classified based on:- (i) Material of construction (ii) Supporting Action (iii) Shape 2) Well foundation:- (a) Caissons:- (i) Open caissons (ii) Box caissons (iii) Pneumatic Caissons

TYPES OF DEEP FOUNDATION

1) Material of construction :-1. Timber piles:- This pile is made up

of timber. The head of pile is covered by steel cap to avoid shattering of timber in case of hammering.

2. Concrete piles:- Concrete piles are used for deep foundations. These piles are either pre-cast or cast-in- situ piles.

3. Steel piles:- Steel piles are either of rolled steel section or fabricated shape or it may be sheet pile.

PILE FOUNDATION:-

Steel (H) Piles

2) Supporting action:-

1. Bearing piles:- When piles transfer load of the building through a soft soil strata to a suitable bearing stratum at greater depths then it is called a bearing pile, in which the pile rests on hard strata at greater depths.

2. Friction piles :- When piles transfer the loads only by means of skin resistance without any end bearing then the piles are called friction piles. No hard strata at end of piles.

3) Shape:-1.Under-reamed piles:- Under-reamed piles are commonly used in black cotton soils which swell and shrink to a greater extent when in contact with water. This is a bored-in-situ pile provided with one or more spreads or bulbs along its length known as under-reamed piles.

2.Tapered piles :-

These piles are used only to increase the density of sub-soil by driving these piles in the loose soils.

Advantages of pile foundations :

The cost of excavation is considerably low.

Dewatering is not required.

Length of pile can be easily adjusted as per

requirements

No temporary supports required, as required in

shallow foundations where open excavations

are done.

2) Well foundation:-

Caissons:-

Caissons is a water tight structure preferably made of wood , steel, R.C.C. , constructed in connection with excavation for the foundation of bridges , piers, in rivers.

Types of caissons:-1. Open Caisson

2. Box caisson

3. Pneumatic caisson

Caisson is a type of well foundation.

1. Open Caisson :- It is a box type structure which is open at the top and at the bottom. Open caisson are normally used on sandy soil or soft bearing stratum In open caisson , walls are constructed in rein forced cement concrete.

2. Box caisson :-

Box caisson is similar to open caisson, only difference is that it is closed at bottom. The middle portion is filled with sand or gravel and lower portion is filled with concrete.

3. Pneumatic caisson:-

1) This type of caissons is open at the bottom and close at the top.

2) Pneumatic caisson is specially used at the place where it is not possible to construct the well.

3) It is suitable for the depth of water more than 12 m.

Conclusion :-

Foundation is the most important part of building structure. Hence it should have good durability , good strength and maintain of quality.

REFERENCES:-

Mrs. Pooja Pawar (building construction book)

THANK YOU !