Introduction

FOUNDATIONSTHEORYRELEVANT CODESTYPES OF FOUNDATIONSHALLOW FOUNDATIONActual soil pressure distribution.Pressure DiagramsMoment CalculationConcept on one-way and two-way shearTypes of footing: Spread, Combined, Strip, Strap, Mat/RaftOn-Site ImagesDEEP FOUNDATIONPile FoundationCaissonsOn-Site ImagesMACHINE FOUNDATIONCONTENTSFOUNDATION

Every structure consists of two parts:SuperstructureSubstructureIt is the lowest part of a structure which is constructed below the ground level.

The function of foundation is to transmit the weight of super structure to the sub soil. 31IS 1080:1985Code of practice for design and construction of shallow foundations in soils (other than raft, ring and shell) (second revision)2IS 2911Design and construction of pile foundations.Parts: 1 to 43IS 1498:1970Classification and identification of soils for general engineering purposes (first revision)4IS 1888:1982Method of load test on soils (second revision)5IS 1892:1979Code of practice for subsurface investigation for foundations (first revision)6IS 1904:1986Code of practice for design and construction of foundations in soils: General requirements (third revision)RELEVANT INDIAN STANDARD CODESTYPES OF FOUNDATIONSSHALLOW FOUNDATIONS (D= B)

DBGLFOUNDATION TRENCH5 It defined as the depth of foundation is less than or equal to Breadth of foundation. Shallow foundations are generally for 2 to 3m depthTYPES OF FOUNDATIONSSHALLOW FOUNDATIONSSPREAD FOUNDATIONSTRIP FOUNDATIONSTRIP FOUNDATIONCOMBINED FOUNDATIONMAT or RAFT FOUNDATION

2. DEEP FOUNDATIONSPILE FOUNDATIONSUNDER-REAMED PILEWELL FOUNDATIONS

6SHALLOW FOUNDATIONSPREAD FOUNDATIONCOMBINED FOUNDATIONSTRIP FOUNDATIONSTRIP FOUNDATIONMAT or RAFT FOUNDATION

AS PER IS 1904:1986ACTUAL SOIL PRESSURE DISRTIBUTION

PRESSURE DIAGRAMS

PRESSURE DIAGRAMS

MOMENT CALCULATION The footing needs to be reinforced for the bending moment producing from upward footing pressure.

The factored moment at the critical section can be calculated as

Mu = Qu * l2/2

WhereQu = factored footing pressurel = the distance from the face of column to the edge of footing.

Design as slab type.CONCEPT OF ONE WAY SHEAR

CONCEPT OF TWO WAY SHEAR

SPREAD FOUNDATIONS15

A spread footing is provided to support an individual column. A spread footing is circular, square or rectangular slab of uniform thickness. Sometimes it is stepped or haunched to spread the load over a large area.15MODEL OF ECCENTRIC FOOTING16

16COMBINED FOOTINGA combined footing supports two columns. A combined footing is provided in the following situations :(i) When two columns are so close to each other that their individual footings would overlap.(ii) When the property line is so close to one column that a spread footing would be eccentrically loaded when kept entirely within the property line.A combined footing may be rectangular or trapezoidal in plan.

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DEFLECTED SHAPESCOMBINED FOOTING

COMBINED FOOTING

STRIP FOOTINGA strip footing is provided for a load bearing wall.A strip footing is also provided for a row of columns which are so closely spaced that their spread footings overlap each other. A strip footing is also known as continuous footing.

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DEFLECTED SHAPESSTRAP FOOTINGA strap footing consists of two isolated footings connected with a structural strap or a lever. The strap connects the two footings such that they behave as one unit. The strap simply acts as a connecting beam and does not take any soil reaction.A strap footing is also known as cantilever footing.

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MAT / RAFT FOUNDATIONSA mat or raft foundation is a large slab supporting a number of columns and walls under the entire structure.A mat is required when the allowable soil pressure is low or where the columns and walls are so close that individual footings would overlap or nearly touch each other.Mat foundations are useful in reducing the differential settlements on non- homogeneous soils or where there is a large variation in the loads on individual columns.

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DEFLECTED SHAPESTYPES OF RAFTRIBBED RAFT

SOLID RAFT

RAFT WITH HIDDEN BEAMS

MIXED RAFTRIBBED RAFT

SOLID RAFT

SOLID RAFT

RAFT FOUNDATION WITH HIDDEN BEAMMIXED RAFT FOUNDATION

ON SITE SHALLOW FOUNDATION

ISOLATED FOOTING CONCRETING OPERATION

ISOLATED FOOTING BEING CURED

ISOLATED FOOTINGON SITE SHALLOW FOUNDATION

ISOLATED FOOTING STEEL CAGEON SITE SHALLOW FOUNDATION

RETROFITTING OF COLUMN AND FOUNDATIONON SITE SHALLOW FOUNDATION

COMBINED FOOTING

ON SITE SHALLOW FOUNDATION

STEPPED WALL FOOTINGON SITE SHALLOW FOUNDATION

RAFT FOUNDATIONON SITE SHALLOW FOUNDATION

RAFT FOUNDATIONON SITE SHALLOW FOUNDATIONAT AIRPORT, BARODA

COMBINED FOOTINGISOLATED FOOTINGAT AIRPORT, BARODA

COMBINED FOOTINGAT AIRPORT, BARODACOMBINED FOOTING

DEEP FOUNDATIONPILE FOUNDATIONSUNDER-REAMED PILEWELL FOUNDATIONS

AS PER IS 1904:1986

PILE FOUNDATIONSThe pile foundations are used in the following conditions:The strata below the ground surface is highly compressible and very weak.The plan of the structure is irregular.Load coming from the structure is very large and distribution is uneven.It is required to transmit structural loads through deep water to a firm stratum; construction on sea shore.When deep drainage lines or canals are passing close to the structure.46PILESEND BEARING PILES FRICTION PILESANCHOR PILESTENSION PILESCOMPACTION PILESCLASSIFICATION OF PILESBASED ON FUNCTIONCLASSIFICATION OF PILESBASED ON MATERIALS AND COMPOSITIONPILESCONCRETE PILESTIMBER PILESSTEEL PILESCOMPOSITE PILESPRE-CAST PILESCAST-IN SITU PILESH - PILEPIPE PILESHEET PILECONCRETE AND TIMBERCONCRETE AND STEEL

TYPES OF PILE48END BEARING PILEThese piles are used to transfer load through water or soft soil to a suitable bearing stratum.

End-Bearing Piles are driven till hard strata of soil is achieved.

Normally these are very short piles.SOFT SOIL

FRICTION PILEWhen a pile is driven into soil of fairly uniform consistency and the tip is not seated in a hard layer, the load-carrying capacity of the pile is developed by skin friction.

These piles are used to transfer loads to a depth of a friction load carrying material by means of skin friction along the length of pile.

COMPACTION PILECOMPACTION PILEThese piles are used to compact loose soils, thus increasing their bearing capacity.

The compaction piles themselves do not carry any load. Hence they may be of weaker material (sand).

The pile tube, driven to compact the soil, is gradually taken out and sand is filled in its place thus forming a sand pile.NUMBER AND SPACING OF PILES

The spacing for end bearing piles, can be much less than for friction piles.

DRIVEN PILES: In the case of loose sandy soils, the piles may be placed at closer intervals.In case of saturated clay or silty soils, greater spacing between piles is required.CAST IN SITU:The soils adjacent to the piles are not stressed to that extent and as such smaller spacings are permitted.

The spacing of piles depends upon:Method of installing the piles.Type of soilNUMBER AND SPACING OF PILES

The spacings for straight uniform diameter piles may vary from 2 to 6 times the diameter of the shaft. For friction piles, the minimum spacing recommended is 3d where d is the diameter of the pile. For end bearing piles passing through relatively compressible strata, the spacing of piles shall not be less than 2.5d.For end bearing piles passing through compressible strata and resting in stiff clay, the spacing may be increased to 3.5d.For compaction piles, the spacing may be 1d.UNDER REAMED PILEIn black cotton soils and other expansive type of soils, buildings often crack due to relative ground movements. This is caused by alternate swelling and shrinking of the soil due to changes in its moisture content.

The under-reamed pile is used to safe guard this movement effectively. Generally this foundation is used for machine foundation, factory building, transmission line towers and other tall structures also.

Best Suited for Friction Piles in Granular Soils.Timber is most suitable for long cohesion piling and piling beneath embankments. Timber piles are usually square sawn hardwood or softwood with section sizes ranging from 225mm to 600mm.They are easy to handle and can be driven by percussion with the minimum of experience.Most timber piles are fitted with an iron or steel driving shoe and have an iron ring around the head to prevent splitting due to driving.For timber piles of length less than 14 meters, the diameter of the tip should be greater than 150 mm. If the length is greater than 18 meters a tip with a diameter of 125 mm is acceptable. TIMBER PILES

STEEL PILESBest Suited for Toe Bearing on Rock.Steel / Iron piles are suitable for handling and driving in long lengths. Their relatively small cross-sectional area combined with their high strength makes penetration easier in firm soil. They are used mainly in conjunction with marine structures and where overlying soils are very weak.These piles are relatively light and therefore are easy to handle and drive.They can be easily cut off or joined by welding. Splicing is carried out by site welding to form piles up to 15 m long with load bearing capacities up to 600 KN.It is common to allow for an amount of corrosion in design by simply over dimensioning the cross-sectional area of the steel pile.

H-PILE DRIVEN USING RAVITY DROP HAMMERPRECAST CIRCULAR-SECTION PILE DRIVEN BY DIESEL HAMMERON SITE PILE FOUNDATION

ON SITE PILE FOUNDATION

AUGER ROTARY PILE BEING INSERTED

ON SITE PILE FOUNDATIONSTEEL CAGE OF PILE

ON SITE PILE FOUNDATIONINSERTION OF CASINGON SITE PILE FOUNDATION

PILE HOLE WITH CASING

REINFORCEMENT BEING INSERTED IN A LARGE ROTARY PILE

ON SITE PILE FOUNDATIONON SITE PILE FOUNDATIONCONCRETING OF THE PILE

ON SITE PILE FOUNDATION

TESTING OF PILES

FAILURE OF FRICTION PILES

AT CINEMAX, BARODAAT AIRPORT, BARODA

CASSIONS FOUNDATION A cassion is a boxlike structure, round, square or rectangular in shape, which is sunk from the surface of either land or water to some desired depth. The Cassions are of three types.Open cassion or well foundationBox cassionPneumatic cassionOpen Cassions are called wells. Well foundations have their origin in India. A foundations have been used in India for hundreds of years for providing deep foundation below the water level for monuments, bridges and aqueducts. Taj Mahal at Agra got well foundations.

68Well foundation is a box of timber, metal, reinforced concrete or masonry which open both at the top and bottom, and is used for building for building and bridge foundations.Types of well shapes:CircularRectangularDouble DTwin circularWELL FOUNDATIONCUTTING EDGECURBSTEININGBOTTOM PLUGTOP PLUGWELL CAPPIERWELL FOUNDATIONSAND FIILING

Control postpontoonBallast watergrabGround water levelCircumferential gapshoe

Open caissonBox caissonTYPES OF CAISSONS

PNEUMATIC CAISSONLarge inverted box on which pier is built.Compressed air is used to keep the water and mud out.Used to work on riverbed or quicksand's. ON SITE CAISSONS

ON SITE CAISSONS

ON SITE CAISSONS

The analysis and design of structure or foundation subjected to vibratory loading is a complex problemIn majority of the cases the machines are supported on a simple concrete block.

TYPESBLOCK TYPEFRAME TYPEMACHINE FOUNDATION

The Analysis of the Machine foundation is done in two stages:

Dynamic Analysis : Includes determination of the natural frequencies of the Machine foundation system and calculation of amplitudes of displacements and rotations of the foundation under dynamic loading.

Static Analysis: Includes check for strength of the foundation, stability of the foundation and check for soil bearing capacityTHANK YOU