Lecture Geotech Engineering

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NPTEL Video Course on Geotechnical Earthquake Engineering by Prof. Deepankar Choudhury Professor, Dept. of Civil Engg., Indian Institute of Technology (IIT) Bombay Powai, Mumbai 400076, India. Email: [email protected] URL: http://www.civil.iitb.ac.in/~dc/ Lecture 1

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Geotech Engineering

Transcript of Lecture Geotech Engineering

Page 1: Lecture Geotech Engineering

NPTEL Video Course on

Geotechnical Earthquake

Engineering

by

Prof. Deepankar Choudhury Professor, Dept. of Civil Engg.,

Indian Institute of Technology (IIT) Bombay

Powai, Mumbai 400076, India.

Email: [email protected]

URL: http://www.civil.iitb.ac.in/~dc/

Lecture – 1

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D. Choudhury, IIT Bombay, India

Course Outline This course on Geotechnical Earthquake Engineering introduces the

fundamental concepts of earthquake engineering related to

geotechnical problems, principles of earthquake, wave propagation,

dynamic soil properties, liquefaction and seismic design of various

geotechnical structures. This course focuses on seismic hazard analysis

which includes both Probabilistic Seismic Hazard Analysis (PSHA)

and Deterministic Seismic Hazard Analysis (DSHA), followed by site

response analysis. Also, behaviour of various geotechnical structures

such as shallow and deep foundations, retaining structures, slopes,

ground anchors, waterfront retaining structures, reinforced soil-wall,

tailing dam due to earthquake loading are discussed with reference to

codal provisions. The course material on Geotechnical Earthquake

Engineering will be very useful to the post-graduate students,

researchers, teachers and practitioners. A number of selected problems

will be solved to illustrate the concepts clearly.

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D. Choudhury, IIT Bombay, India

Course Contents Introduction, Basic Vibration theory, Engineering

Seismology, Strong Ground Motion, Wave

Propagation, Dynamic Soil Properties, Seismic Hazard

Analysis, Site Response Analysis, Dynamic Soil-

Structure Interaction, Applications of Earthquake

Engineering to various Geotechnical Engineering

Problems like Retaining Walls, Foundations, Anchors,

Piles, Tailing Dams, Landfills, Slopes, Waterfront

Retaining Walls/Sea Walls, Reinforced Soil-Walls,

Liquefaction, Hazard Mapping etc.

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D. Choudhury, IIT Bombay, India

Course Modules

Total about NINE (9) Modules:

Module – 1: Introduction to Geotechnical Earthquake

Engineering

Module – 2: Basics of Vibration Theory

Module – 3: Engineering Seismology

Module – 4: Strong Ground Motion

Module – 5: Wave Propagation

Module – 6: Dynamic Soil Properties

Module – 7: Seismic Hazard Analysis

Module – 8: Site Response Analysis

Module – 9: Seismic Analysis and Design of Various

Geotechnical Structures

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D. Choudhury, IIT Bombay, India

Pre-Requisite • Soil Mechanics / Geotechnical

Engineering (Mandatory)

• Soil Dynamics (Optional)

Audience

Post-Graduate (High Caliber Bachelors,

Masters and PhD) Students, Teachers,

Practitioners, Designers, Academicians,

Decision Makers

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D. Choudhury, IIT Bombay, India

References 1. Steven L. Kramer, “Geotechnical Earthquake Engineering”, Prentice

Hall Inc.

2. Robert W. Day, “Geotechnical Earthquake Engineering Handbook”,

McGraw Hill, New York.

3. Ikuo Towhata, “Geotechnical Earthquake Engineering”, Springer-

Verlag Heidelberg.

4. Kenji Ishihara, “Soil Behaviour in Earthquake Geotechnics”, Oxford

University Press, USA.

5.Shamsher Prakash, “Soil Dynamics”, McGraw-Hill Book Company.

6. Milutin Srbulov, “Geotechnical Earthquake Engineering: Simplified

Analyses with Case Studies and Examples”, Springer-Verlag.

7. IS 1893, Indian Standard Criteria for earthquake resistant Design of

Structures.

ADDITIONAL READINGS (MUST)

• Journal and Conference papers in the area of Geotechnical Earthquake

Engineering.

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D. Choudhury, IIT Bombay, India

Module – 1

Introduction to Geotechnical

Earthquake Engineering

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Effects of Earthquake • Devastating effects of earthquakes due to failure of structure

Earthquake never kills,

but damage of structures

during earthquake due to

incorrect or insufficient

design and

constructions kills

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Effects of Earthquake • Devastating effects of earthquakes due to failure of soil beneath

Buildings dilapidated because of failure of soil beneath

Structure is safe, but

it has settled down

by huge amount,

due to failure of

ground beneath.

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Effects of Earthquake • Devastating effects of earthquakes due to landslides and rockslides

Fig. Landslides in Sikkim during 2011 earthquake

Fig. Rockslides in Sikkim at different road streches

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• Tsunami – is a series of water waves caused by the displacement of a large

volume of a body of water, typically an ocean or a large lake.

– Tsunami is a Japanese word with the English translation, "harbor wave” ("tsu," means harbor, while "nami," means "wave“)

Effects of Earthquake

Figures showing disasters due to Tsunami

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Principal Types of Earthquake Damage

Structural

Caused by excessive ground shaking

Strongly influenced by local soil conditions

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• Ground Shaking: Shakes structures constructed on

ground causing them to collapse

• Liquefaction: Conversion of formally stable

cohesionless soils to a fluid mass, causing damage to

the structures

• Landslides: Triggered by the vibrations

• Retaining structure failure: Damage of anchored

wall, sheet pile, other retaining walls and sea walls

• Fire: Indirect result of earthquakes triggered by broken

gas and power lines

• Tsunamis: large waves created by the instantaneous

displacement of the sea floor during submarine faulting

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Damage due to Earthquakes

Earthquakes have varied effects, including changes in

geologic features, damage to man-made structures and

impact on human and animal life.

Earthquake Damage depends on many factors:

The size of the Earthquake

The distance from the focus of the earthquake

The properties of the materials at the site

The nature of the structures in the area

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Ground Shaking Frequency of shaking differs for different seismic waves.

High frequency body waves shake low buildings more.

Low frequency surface waves shake high buildings more.

Intensity of shaking also depends on type of subsurface material.

Unconsolidated materials amplify shaking more than rocks do.

Buildings respond differently to shaking depending on construction styles, materials

Wood -- more flexible, holds up well

Earthen materials, unreinforced concrete -- very vulnerable to

shaking.

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Collapse of Buildings

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Collapse of Buildings

(Fukui Earthquake, 1948) June 28th (Mon), 1948

16:13 pm

M7.1, D=0km

Death Toll: 3,769

Injured: 22,203

Collapse Ratio of

Houses: almost 100%

(The Area of South-

North 20km by East-

West10km of Fukui

Plain)

Damage to Pile-Heads of

Hokuriku Haiden Building.

(Shear Cracks)

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Collapse of Buildings

(Fukui Earthquake, 1948)

Damage to the Pile Foundations of

Hokuriku-Haiden Building caused by the 1948

Fukui Earthquake

Settlements of the First Floor

Cracks at the Column-Heads of

the Second Floor and the Floor

Slabs of the First Floor

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Soft first story/inadequate shear strength

Loma Prieta earthquake damage in San Francisco. The soft first story is due to construction of garages in the first story and resultant

reduction in shear strength. (Photo from: http://earthquake.usgs.gov/bytopic/photos.html)

On October 17, 1989, at 5:04:15 p.m. (P.d.t.), a magnitude 6.9 (moment magnitude; surface-wave magnitude, 7.1)