FOUNDATION AND ITS FOUNDATION AND ITS TYPESTYPES

Prepared Prepared BBy:y:--Satish Kambaliya(11bcl016)Satish Kambaliya(11bcl016)Satish Kambaliya(11bcl016)Satish Kambaliya(11bcl016)

Civil Engineering DepartmentCivil Engineering DepartmentInstitute Of Technology Institute Of Technology NirmaNirma University, University,

AhmedabadAhmedabad

INTRODUCTIONINTRODUCTION

�� As we know tree cannot stand without roots such a way building As we know tree cannot stand without roots such a way building cannot stand without foundation and it is most important in cannot stand without foundation and it is most important in construction.construction.

�� FoundationFoundation,, Part of a structural system that supports and anchors Part of a structural system that supports and anchors the superstructure of a building and transmits its loads directly to the superstructure of a building and transmits its loads directly to

the earth .the earth .The foundation provides an anchor from wind and The foundation provides an anchor from wind and the earth .the earth .The foundation provides an anchor from wind and The foundation provides an anchor from wind and

seismic forces, which can move a house and damage itseismic forces, which can move a house and damage it. . It keeps It keeps moisture out of the crawl space or basement.moisture out of the crawl space or basement.

TYPES OF FOUNDATIONTYPES OF FOUNDATION

�� There are mainly two types of foundations. There are mainly two types of foundations.

1).Shallow Foundation1).Shallow Foundation

2).Deep Foundation2).Deep Foundation

DETAILS ON SHALLOW FOUNDATION DETAILS ON SHALLOW FOUNDATION

Shallow Foundation:Shallow Foundation:--According to Terzaghi, a foundation is According to Terzaghi, a foundation is

term as shallow if its width is more than its depth. This transfer term as shallow if its width is more than its depth. This transfer load primarily through shear resistance of bearing strata and are load primarily through shear resistance of bearing strata and are normally laid to a depth of 3m.normally laid to a depth of 3m.

Types of shallow foundationTypes of shallow foundation

�� 1).Spread Footing Foundation1).Spread Footing Foundation

�� 2).Mat Foundation2).Mat Foundation

�� 3).Combined Footing Foundation3).Combined Footing Foundation

�� 4).Strip Foundation4).Strip Foundation

�� 5).Strap Footing Foundation5).Strap Footing Foundation

�� 6).Ring And Shell .6).Ring And Shell .

�� 7).Machine Foundation7).Machine Foundation

1). Spread Footing Foundation1). Spread Footing Foundation

A spread footing foundation, which is typical in residential A spread footing foundation, which is typical in residential building, has a wider bottom portion than the loadbuilding, has a wider bottom portion than the load--bearing bearing foundation walls it supports. This wider part "spreads" the weight foundation walls it supports. This wider part "spreads" the weight of the structure over more area for greater stabilityof the structure over more area for greater stability..

A spread footing which changes elevation in several places in a A spread footing which changes elevation in several places in a series of vertical "steps" in order to follow the contours of a series of vertical "steps" in order to follow the contours of a sloping site or accommodate changes in soil strata, is termed a sloping site or accommodate changes in soil strata, is termed a stepped footing.stepped footing.

2).Strip Foundation 2).Strip Foundation

�� A foundation is required to ensure loads from the building are A foundation is required to ensure loads from the building are sustained and safely transmitted to the ground. sustained and safely transmitted to the ground.

�� All load bearing elements, these include external walls, party All load bearing elements, these include external walls, party walls, chimney breasts, piers and internal load bearing walls walls, chimney breasts, piers and internal load bearing walls should sit on an adequate foundation. should sit on an adequate foundation. should sit on an adequate foundation. should sit on an adequate foundation.

�� Foundation DepthFoundation Depth

Angle Of Spread Of Load

3).Raft Foundation3).Raft Foundation

�� A raft foundation is essential a mat foundation.A raft foundation is essential a mat foundation.

�� The purpose of a mat foundation is when you a building built on The purpose of a mat foundation is when you a building built on a site with low soil bearing conditions. A raft foundation is use to a site with low soil bearing conditions. A raft foundation is use to distribute the building pressure over a large area so the soil can distribute the building pressure over a large area so the soil can bear the stress.bear the stress.bear the stress.bear the stress.

�� A raft foundation normally consists of a concrete slab which A raft foundation normally consists of a concrete slab which extends over the entire loaded area.extends over the entire loaded area.

�� Raft foundations have the advantage of reducing differential Raft foundations have the advantage of reducing differential settlements as the concrete slab resists differential movements settlements as the concrete slab resists differential movements between loading positions. between loading positions.

Types of Raft FoundationTypes of Raft Foundation

�� Raft foundation can be considered of three typesRaft foundation can be considered of three types

a). Solid slab rafts.a). Solid slab rafts.b). Beam and slab rafts.b). Beam and slab rafts.c). Cellular rafts. c). Cellular rafts.

a). Solid slab raft foundationa). Solid slab raft foundation

b). b). Beam and slab raft foundationBeam and slab raft foundation

c). Cellular raft foundationc). Cellular raft foundation

4).4).Combined Footing FoundationCombined Footing Foundation

�� A combined footing is usually used to support two columns of A combined footing is usually used to support two columns of unequal loads. unequal loads.

�� Another case where a combined footing is an efficient Another case where a combined footing is an efficient foundation solution is when there are two interior columns which foundation solution is when there are two interior columns which foundation solution is when there are two interior columns which foundation solution is when there are two interior columns which are so close to each other that the two isolated footings stress are so close to each other that the two isolated footings stress zones in the soil areas would overlap.zones in the soil areas would overlap.

�� The area of the combined footing may be proportioned for a The area of the combined footing may be proportioned for a uniform settlement by making its centroid coincide with the uniform settlement by making its centroid coincide with the resultant of the column loads supported by the footing resultant of the column loads supported by the footing

5).Machine foundation5).Machine foundation

�� Machine foundations require a special consideration because they Machine foundations require a special consideration because they transmit dynamic loads to soil in addition to static loads due to transmit dynamic loads to soil in addition to static loads due to weight of foundation, machine and accessories.weight of foundation, machine and accessories.

�� A suitable foundation is selected, depending upon the type of A suitable foundation is selected, depending upon the type of �� A suitable foundation is selected, depending upon the type of A suitable foundation is selected, depending upon the type of machine. machine.

�� For compressors and reciprocating machines, a block foundation For compressors and reciprocating machines, a block foundation is generally provided. Such a foundation consists of a pedestal is generally provided. Such a foundation consists of a pedestal resting on a footing. resting on a footing.

2).Deep Foundation2).Deep Foundation and its Typesand its Types

�� According to Terzaghi, a foundation is term as deep if its According to Terzaghi, a foundation is term as deep if its width is less than its depth. Here depth is greater than 3m. width is less than its depth. Here depth is greater than 3m.

�� Types of deep foundationTypes of deep foundation1).Pile Foundation1).Pile Foundation1).Pile Foundation1).Pile Foundation

2).Caissons Foundation2).Caissons Foundation

Geotechnical InvestigationGeotechnical Investigation

�� Before the laying deep foundation following geological Before the laying deep foundation following geological investigation should be laid down.investigation should be laid down.

1).Recommended deep foundation types and installed capacity.1).Recommended deep foundation types and installed capacity.2).Recommended center to center spacing of deep foundation 2).Recommended center to center spacing of deep foundation 2).Recommended center to center spacing of deep foundation 2).Recommended center to center spacing of deep foundation elements.elements.3).Driving criteria.3).Driving criteria.4).Installation procedure.4).Installation procedure.5).Load test requirement.5).Load test requirement.6).Designation of bearing strata.6).Designation of bearing strata.7).Suitability of deep foundation material for environment 7).Suitability of deep foundation material for environment

Details on some types of Deep FoundationDetails on some types of Deep Foundation

�� 1). Piles Foundation:1). Piles Foundation:--Piles are relatively long, slender Piles are relatively long, slender

members that transmit foundation loads through soil strata of low members that transmit foundation loads through soil strata of low bearing capacity to deeper soil or rock strata having a high bearing capacity to deeper soil or rock strata having a high bearing capacity. bearing capacity. bearing capacity. bearing capacity.

�� Piles foundation can be broadly classified as follow.Piles foundation can be broadly classified as follow.1). Types of pile 1). Types of pile

2). Types of construction 2). Types of construction

3). Factors influencing choice 3). Factors influencing choice

4). Pile groups 4). Pile groups

Types of pileTypes of pile

�� End bearing piles End bearing piles

�� Friction piles Friction piles

�� Settlement reducing piles Settlement reducing piles �� Settlement reducing piles Settlement reducing piles

�� Tension piles Tension piles

�� Laterally loaded piles Laterally loaded piles

�� Piles in fillPiles in fill

Types of pile construction Types of pile construction

�� Displacement piles Displacement piles

�� NonNon--displacement piles displacement piles

Displacement pilesDisplacement piles

�� Totally preformed displacement piles Totally preformed displacement piles

�� Driven and castDriven and cast--inin--place displacement piles place displacement piles

�� Helical (screw) castHelical (screw) cast--inin--place displacement piles place displacement piles

�� Methods of installationMethods of installation�� Methods of installationMethods of installation

Methods of installationMethods of installation

�� Dropping weight Dropping weight

�� Diesel hammer Diesel hammer

�� Vibratory methods of pile driving Vibratory methods of pile driving

�� Jacking methods of insertion Jacking methods of insertion

NonNon--displacement pilesdisplacement piles

�� Small diameter bored castSmall diameter bored cast--inin--place piles place piles

�� Large diameter bored castLarge diameter bored cast--inin--place piles place piles

�� Partially preformed piles Partially preformed piles

�� Grout or concrete intruded piles Grout or concrete intruded piles

Factors influencing choice of pileFactors influencing choice of pile

�� Ground conditions Ground conditions

�� Durability Durability

�� CostCost

�� Location and type of structure Location and type of structure

2).Caissons Foundation2).Caissons Foundation

�� The foundation system of and the soils beneath the building The foundation system of and the soils beneath the building prevent the complex from moving vertically. prevent the complex from moving vertically.

�� What is CaissonsWhat is Caissons�� It’s a prefabricated hollow box or cylinder.It’s a prefabricated hollow box or cylinder.

�� Drilled shafts can be used to sustain high axial and lateral loads. Drilled shafts can be used to sustain high axial and lateral loads. �� Drilled shafts can be used to sustain high axial and lateral loads. Drilled shafts can be used to sustain high axial and lateral loads. Typical shaft diameters range from 18 to 144 inches Typical shaft diameters range from 18 to 144 inches

Types of CaissonsTypes of Caissons

�� Box CaissonsBox Caissons

�� Excavated CaissonsExcavated Caissons

�� Floating CaissonsFloating Caissons

�� Open CaissonsOpen Caissons

�� Pneumatic CaissonsPneumatic Caissons

�� Sheeted CaissonsSheeted Caissons

The process: building a caissonThe process: building a caisson