2-introduction foundation engg.pdf

7/29/2019 2-INTRODUCTION Foundation ENGG.pdf

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SYLLABUS of FOUNDATION

ENGINEERING

Soil Exploration

Shallow Foundations

Deep Foundations

Earthen Dams

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SYLLABUS of FOUNDATION

ENGINEERING

Soil Exploration

Importance of soil exploration and planning of soilexploration program. Soil exploration methods:probing, test pits, auger boring, wash boring,percussion and rotary drilling and geophysicalmethods. Disturbed and undisturbed soil

sampling. Soil samplers. Insitu tests: standardpenetration test (SPT), cone penetration test(CPT), plate load test and field vane shear test.Bore hole logs and subsoil exploration report.

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Foundations

Definition, purpose and types of and generalrequirements of foundations. Depth offootings. Selection of foundation type.

Shallow Foundations

Definition of bearing capacity. Methods ofdetermining bearing capacity. Presumptivevalues of bearing capacity. Terzaghi andMeyerhofs theories of bearing capacity anddesign of isolated, combined and stripfootings. Settlement of shallow foundationsand their remedial measures.

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Deep Foundations

Introduction to deep foundations. Types ofpiles. Load carrying capacity of piles. Groupaction. Settlement. Negative skin friction. Pileload test. Cassion and well foundations.

Earthen Dams

Types of earthen dams, components and theirfunctions. General design considerations and

typical cross- section.

Foundations on difficult soils

Intoduction to relevant softwares.

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TextPrinciples of

FoundationEngineering

by Braja M.Das

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ReferenceSoil

Mechanics &Foundations

by MuniBudhu

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ReferenceFoundation

Analysisand Design

by Joseph E. Bowles

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ReferenceFoundationDesign

by DonaldP. Coduto

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Definition Foundation is a part of the structure that

supports the structural weight and transmitsthe load to underlying soil or rock.(Foundationincludes foundation structure and soilinfluenced by the structural load.)

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Types of FoundationsShallow Foundations versus Deep

Foundations

Foundations

ShallowFoundations

DeepFoundations

SpreadFootings

MatFoundations

DrivenPiles

DrilledShafts

Auger CastPiles

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FoundationsShallow Footings

Spread Footing

Mat Footing Combined Footing

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Deep Foundation

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Shoes, Snow shoes, and stilts are much likethe different types of footings of a structure

A Shoe make contact with a firm

surface (spread footings)

B. Snow shoes spread weight

over a large surface (raft footing).

C. Stilts (pile footings)reach firm surface

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Parts of a FoundationA foundation (substructure) can

be divided into three parts

Bearing surface.

Footing.

Upright supports.

The bearing surface is theearth upon which the

foundation rests. It may be soilor bedrock. The bearing surfacemay be far below the surface ofa swamp, river, or ocean.

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The footing is the flat part of the foundation.It spreads the load of the structure above it.

Upright support. They may be walls orpiers (masonry column) that rise above thefooting. They form the rest of the structure.

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Foundation System

This part will be doneby the Structural

Engineer

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Every civil engineering structure such as : Buildings

Bridges.

Highway pavement ,and

Railway track

Will have asuperstructure and

substructure(Foundations)

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Super structure transmits the load. Sub structure receives and transmits the

load to underlying soil or rock.

The foundation engineers aim is that nocomponent of the structure and foundationshould experience of any kind of distress.

Geotechnical design parameters:- Bearing capacity

- Settlement

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What is Foundation Engineering?

The art of selecting, designing, and constructingstructural support systems based on scientific

principles of soils and engineering mechanics

incorporating accumulated experience with

such applications.

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What is the currentstate-of-the-art?

In spite of the many advances in foundation

engineering it is still an art mostly supported

by empirical techniques.

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Why mostly empirical?We do not fully understand the

behavior of foundations.

Knowledge of subsurface conditions

are always limited.

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What do I have to know to be a

good Foundation Engineer?Geology

Geophysics

Subsurface Exploration

Laboratory Testing

Soil Mechanics

Structural Engineering

Construction Engineering

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Uncertainties

Soils:Not a manufactured material

High degree of variability

Material characterization done basedon a small sample

Complex behavior (non-linear;

anisotropic)Rationalism vs. Empiricism

Factors of Safety

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Who is responsible for

uncertainties?You (the Foundation Engineer).

Always use presence, common senseengineering, and experience first, beforefirst, beforefirst, beforefirst, before

blindly following analysis and test results.

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What is analysis good for?It is good to confirm that a

precedent solution can be safelyapplied to your site.

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Is it my job to be concerned of

costs?Yes. As a professional engineer, it is your

obligation to balance costs anduncertainties

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The Final Question

In Foundation Engineering, there areIn Foundation Engineering, there areIn Foundation Engineering, there areIn Foundation Engineering, there are

manymanymanymany ififififssss andandandand butbutbutbutssss. What do I do. What do I do. What do I do. What do I do

when I am in doubt?when I am in doubt?when I am in doubt?when I am in doubt?1. When in doubt go wide.

2. When in doubt go deep.

3. When in doubt grout (ground modify).

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Eiffel Tower, Paris, France,built in 1887-1889

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Leaning Tower, Pisa, Italy

Built 1173-1350

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Palacio de las BellasArtes, Mexico CityBuilt 1932-1934

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Tower of LatinoAmericana, Mexico CityBuilt in 1956

44 stories; 597-ft

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Performance Requirements

Design Loads

Allowable Stress Design vs LRFD

Performance Requirements

Strength Requirements

Serviceability Requirements

Total Settlement

Differential Settlement

Constructability Requirements

Economic Requirements

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Strength RequirementsFoundation

soil must bestrongenough tosupportimposedloads ..

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Failure of a Bridge FoundationDo

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Serviceability RequirementsSettlement must

be withinacceptable limits..

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Total vs. Differential SettlementDo

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Geotechnical Aspects

Determining the type of foundation for the structure,Determining the type of foundation for the structure,Determining the type of foundation for the structure,Determining the type of foundation for the structure,including the depth and dimensionsincluding the depth and dimensionsincluding the depth and dimensionsincluding the depth and dimensions

Calculating the potential settlement of the foundationCalculating the potential settlement of the foundationCalculating the potential settlement of the foundationCalculating the potential settlement of the foundation

Determining the expansion potentialDetermining the expansion potentialDetermining the expansion potentialDetermining the expansion potential

Investigating the stability of slopes and their effect onInvestigating the stability of slopes and their effect onInvestigating the stability of slopes and their effect onInvestigating the stability of slopes and their effect on

adjacent foundationsadjacent foundationsadjacent foundationsadjacent foundations

Investigating the possibility of foundation movementInvestigating the possibility of foundation movementInvestigating the possibility of foundation movementInvestigating the possibility of foundation movement

due to seismic forces, which would also include thedue to seismic forces, which would also include thedue to seismic forces, which would also include thedue to seismic forces, which would also include the

possibility of liquefactionpossibility of liquefactionpossibility of liquefactionpossibility of liquefaction

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Performing studies and tests to determine the potentialPerforming studies and tests to determine the potentialPerforming studies and tests to determine the potentialPerforming studies and tests to determine the potential

for deterioration of the foundationsfor deterioration of the foundationsfor deterioration of the foundationsfor deterioration of the foundations

Evaluating possible soil treatment to increase theEvaluating possible soil treatment to increase theEvaluating possible soil treatment to increase theEvaluating possible soil treatment to increase thefoundation bearing capacityfoundation bearing capacityfoundation bearing capacityfoundation bearing capacity

Determining design parameters for retaining wallDetermining design parameters for retaining wallDetermining design parameters for retaining wallDetermining design parameters for retaining wall

foundationsfoundationsfoundationsfoundationsProviding recommendations for dewatering andProviding recommendations for dewatering andProviding recommendations for dewatering andProviding recommendations for dewatering and

drainage of excavations needed for the construction ofdrainage of excavations needed for the construction ofdrainage of excavations needed for the construction ofdrainage of excavations needed for the construction of

the foundationthe foundationthe foundationthe foundation

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Investigating ground water and seepage problems andInvestigating ground water and seepage problems andInvestigating ground water and seepage problems andInvestigating ground water and seepage problems and

developing mitigation measures during foundationdeveloping mitigation measures during foundationdeveloping mitigation measures during foundationdeveloping mitigation measures during foundation

constructionconstructionconstructionconstruction

Site preparation, including compaction specificationsSite preparation, including compaction specificationsSite preparation, including compaction specificationsSite preparation, including compaction specifications

and density testing during gradingand density testing during gradingand density testing during gradingand density testing during grading

Underpinning and field testing of foundationsUnderpinning and field testing of foundationsUnderpinning and field testing of foundationsUnderpinning and field testing of foundations

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General Requirements forFoundation Engineering Projects

Knowledge of the general topography of the siteKnowledge of the general topography of the siteKnowledge of the general topography of the siteKnowledge of the general topography of the site

The location of buried utilitiesThe location of buried utilitiesThe location of buried utilitiesThe location of buried utilities

The geology of the proposed siteThe geology of the proposed siteThe geology of the proposed siteThe geology of the proposed siteThe previous history and use of the siteThe previous history and use of the siteThe previous history and use of the siteThe previous history and use of the site

Any special features such as the possibility ofAny special features such as the possibility ofAny special features such as the possibility ofAny special features such as the possibility of

earthquakes or climate factors such as flooding ,earthquakes or climate factors such as flooding ,earthquakes or climate factors such as flooding ,earthquakes or climate factors such as flooding ,seasonal swelling and shrinkage, permafrost, or soilseasonal swelling and shrinkage, permafrost, or soilseasonal swelling and shrinkage, permafrost, or soilseasonal swelling and shrinkage, permafrost, or soil

erosionerosionerosionerosion

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The availability and quality of local construction materialsThe availability and quality of local construction materialsThe availability and quality of local construction materialsThe availability and quality of local construction materials

For maritime or river structures, information on tidal rangesFor maritime or river structures, information on tidal rangesFor maritime or river structures, information on tidal rangesFor maritime or river structures, information on tidal ranges

and river levels, velocity of tidal and river currents, andand river levels, velocity of tidal and river currents, andand river levels, velocity of tidal and river currents, andand river levels, velocity of tidal and river currents, and otherotherotherother

hydrographic and meteorological datahydrographic and meteorological datahydrographic and meteorological datahydrographic and meteorological data

A detailed record of the soil and rock strata and ground waterA detailed record of the soil and rock strata and ground waterA detailed record of the soil and rock strata and ground waterA detailed record of the soil and rock strata and ground water

conditions within the zones affected by foundation bearingconditions within the zones affected by foundation bearingconditions within the zones affected by foundation bearingconditions within the zones affected by foundation bearing

pressure and construction operationspressure and construction operationspressure and construction operationspressure and construction operations


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Results of laboratory tests on soil andResults of laboratory tests on soil andResults of laboratory tests on soil andResults of laboratory tests on soil and

rock samples appropriate to therock samples appropriate to therock samples appropriate to therock samples appropriate to the

particular foundation design orparticular foundation design orparticular foundation design orparticular foundation design or

construction problemsconstruction problemsconstruction problemsconstruction problems

Results of chemical analyses on soil andResults of chemical analyses on soil andResults of chemical analyses on soil andResults of chemical analyses on soil and

ground water to determine possibleground water to determine possibleground water to determine possibleground water to determine possible

deleterious of foundation structuresdeleterious of foundation structuresdeleterious of foundation structuresdeleterious of foundation structures


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Preliminary Information and Planningthe WorkProject LocationProject LocationProject LocationProject Location

Basic information on the location of the project isrequired. The location of the project can be comparedwith known geological hazards such as active faults,landslides, or deposits prone to liquefaction.

Type of ProjectType of ProjectType of ProjectType of Project

It is important to obtain as much information about theproject as possible.


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Such information could include the type of structure and use,size of the structure including the number of stories, type of

construction and floor systems, preliminary foundation type,and estimated structural loadings.

Scope of workScope of workScope of workScope of work

The scope of the work must be determined, which includessubsurface exploration and laboratory testing to determinethe feasibility of the project, the preparation of foundation

design parameters, and compaction testing during the gradingof the site in order to prepare the building pad for foundationconstruction.


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After the preliminary information is obtained, the next

step is to plan the foundation investigation work.

For minor project, the planning effort may be minimal,

but for large-scale projects, the plan could be quiteextensive and could change as the design andconstruction progresses.


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The planning effort could include the following:

Budget and scheduling considerations

Selection of a team of professionals of relevant fields(such as geotechnical engineer, engineering geologist,

structural engineer, hydro geologist and the like)that willwork on the project

Preliminary subsurface exploration plan, such as number

, location, and depth of borings


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Document collection

Laboratory testing requirements

Types of engineering analyses

that will be required for the design

of the foundation.


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2-introduction foundation engg.pdf

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