SUBJECT NAME: FOUNDATION ENGINEERING SUBJECT CODE: CE 1306 By R.Navaneethan Lecturer Department of...
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Transcript of SUBJECT NAME: FOUNDATION ENGINEERING SUBJECT CODE: CE 1306 By R.Navaneethan Lecturer Department of...
SUBJECT NAME: FOUNDATION ENGINEERING
SUBJECT CODE: CE 1306
ByR.Navaneethan
LecturerDepartment of Civil Engineering
PITS
This subject is introduced to students with well organized five units, to let know the basics of soil mechanics through studying the properties and testing methods available for soil in context with Civil Engineering
OBJECTIVE
FOUNDATION ENGINEERING
TOPICS
SITE INVESTIGATION AND SELECTION OF FOUNDATION
SHALLOW FOUNDATION
FOOTINGS AND RAFTS
PILES
RETAINING WALLS
Foundation Engineering
In a broad sense, foundation engineering is a art of selecting, designing and constructing the elements that transfer the weight of structure to the underlying soil or rock.
The role of engineer is to select the type of foundation, its design and supervision of construction.
Before the engineer can design a foundation intelligently, he must have a reasonably accurate conception of the physical properties and the arrangement of the underlying materials. This requires detailed soil explorations.
Unit I
SITE INVESTIGATION AND SELECTION OF FOUNDATION
• Methods of exploration • Sampling • Penetration tests • Selection of foundation based on soil
condition.
Useful in determining properties of cohesionless soil
Simple and inexpensive
Use a split-spoon sampler
Standard Penetration Test
Unit II SHALLOW FOUNDATION
• Bearing capacity of shallow foundation on homogeneous deposits
• Factors affecting bearing capacity• Methods of minimizing settlement• SPT, SCPT and plate load
Bearing Capacity : Modes of Failure
General shear Failure
Sudden appearance of a clearly defined distinct failure shape
Strip footing in
dense soil
Load q (kN/m2)Settlem
ent (mm
)
Unit III FOOTINGS AND RAFTS
• Types of foundation• Isolated and combined
footings• Mat foundation• Floating foundation
Whenever two or more columns in a straight line are carried on a single spread footing, it is called a combined footing.
Isolated footings for each column are generally the economical.
Combined footings are provided only when it is absolutely necessary, as
Where soil bearing capacity is low, causing overlap of adjacent isolated footings,
Proximity of building line or existing building or sewer, adjacent to a building column,
When two columns are close together, causing overlap of adjacent isolated footings.
Combined Footing
Unit IV PILES
• Factors influencing the selection of pile• Interpretation of pile load test• Forces on pile caps• Capacity under compression and uplift
Pile Load Test
• Load imparted to pile in gradual steps to twice design load, as settlement data recorded
• Often, load removed in steps, too, to produce load-deflection curve
• Behavior– Elastic deformation– Buckling– Puncture
• Ensure multiple deflection references, in case one is lost
Unit V RETAINING WALLS
• Active and passive states• Condition for critical failure plane• Coloumb’s wedge theory• Pressure on the wall due to line load
DESIGN
The designed retaining wall must be able to ensure the following : Overturning doesn’t occur Sliding doesn’t occur The soil on which the wall rests mustn’t be
overloaded The material used in construction are not
overstressed.
TEXT BOOKS Murthy, V.N.S., “Soil Mechanics and Foundation Engineering”, UBS Publishers
Distribution Ltd, 1999
Gopal Ranjan Rao, A.S.R.,”Basic and Applied Soil Mechanics”, Wiley Eastern Ltd., 2003
REFERENCES Das, B.M., “Principles of Foundation Engineering, 5th Edition, Thomson Books,2003
Kaniraj, S.R., “Design Aids in Soil Mechanics and Foundation Engineering”, Tata McGraw Hill Publishing Company Ltd., 2002
Bowles, J.E., “Foundation Analysis and Design”, McGraw-Hill, 1994
• Problems in footings• Problems in retaining walls• Study of Plastic equilibrium in soils
ASSIGNMENT TOPICS
en.wikipedia.org/wiki/Foundation_(engineering)
www.gerionline.org/Library/35.pdf
www.learnerstv.com/Free-Engineering-Video-lectures-ltv185-Page1.htm
www.foundationengineering.info/
www.asce.org/Books.../Art-of-Foundation-Engineering-Practice/
en.wikipedia.org/wiki/Foundation_engineering
URL
UNIT I SITE INVESTIGATION AND SELECTION OF FOUNDATION
Scope and objectives – Methods of exploration-averaging and boring – Water boring and rotatory drilling – Depth of boring – Spacing of bore hole - Sampling – Representative and undisturbed sampling – Sampling techniques – Split spoon sampler, thin tube sampler, stationary piston sampler – Bore log report – Penetration tests (SPT and SCPT) – Data interpretation (Strength parameters and Liquefaction potential) – Selection of foundation based on soil condition.
UNIT II SHALLOW FOUNDATION
Introduction–Location and depth of foundation – Codal provisions – Bearing capacity ofshallow foundation on homogeneous deposits – Terzaghi’s formula and BIS formula –Factors affecting bearing capacity – Problems-bearing Capacity from insitu tests (SPT,SCPT and plate load) – Allowable bearing pressure, settlement – Components ofsettlement – Determination of settlement of foundations on granular and clay deposits –Allowable settlements – Codal provision – Methods of minimizing settlement –Differential settlement.
SYLLABUS
UNIT III FOOTINGS AND RAFTS
Types of foundation – Contact pressure distribution below footings and raft – Isolated and combined footings – Types – Proportioning – Mat foundation – Types – Use –Proportioning – Floating foundation.
UNIT IV PILES
Types of piles and their function – Factors influencing the selection of pile – Carryingcapacity of single pile in granular and cohesive soil – Static formula – Dynamic formulae (Engineering news and Hiley’s) – Capacity from insitu tests (SPT and SCPT) – Negative skin friction – Uplift capacity – Group capacity by different methods (Feld’s rule, Converse Labarra formula and block failure criterion) – Settlement of pile groups –Interpretation of pile load test – Forces on pile caps – Under reamed piles – Capacityunder compression and uplift.
UNIT V RETAINING WALLS
Plastic equilibrium in soils – Active and passive states – Rankine’s theory – Cohesionless and cohesive soil – Coloumb’s wedge theory – Condition for critical failure plane –Earth pressure on retaining walls of simple configurations – Graphical methods (Rebhann and Culmann) – Pressure on the wall due to line load – Stability of retaining walls.