intro to geotechnical eng 1

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GTE301T: GEOTECHNICAL ENGINEERING III

Introduction to Geotechnical Engineering

Dr GM Ochieng’

Tshwane University of Technology - Pretoria

Course Objective

• To provide students with physical, mechanical, and mathematical tools and concepts for the understanding of engineering behaviour of soilsand introduction to engineering design of geotechnical systems.

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Definitions - Soil

• Pedologist:Soil is the substance existing on the earth's surface, which grows and develops plant life.

• Geologist:Soil is the material in the relative thin surface zone within which roots occur, and all the rest of the crust is grouped under the term ROCK irrespective of its hardness. Also: unconsolidated rock, overburden

• Engineer:Soil is the un-aggregated or un-cemented deposits of mineral and/or organic particles or fragments covering large portion of the earth's crust.

(Ref: Tamal Tawfiq 2007)

Definitions

• Soil mechanics is a discipline that applies the principles of engineering mechanics to soils to predict the mechanical behaviour of soil.

• Geotechnical Engineering is the branch of civil engineering that deals with soil, rock, and underground water, and their relation to the design construction and operation of engineering projects (Coduto 1998)

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Content

• Soil Mechanics: – Physical Soil Parameters – permeability

constant

– Seepage though Soils

– Stress and Strain in Soils – Effective Stresses

– Shear Strength parameters in soils

– Deformation in Soils - Consolidation

Content

• Basic Geotechnical Engineering Design– Earth Pressure - Retaining Walls

– Slope Stability

– Bearing Capacity: Shallow and Deep Foundation

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Typical Geotechnical Engineering Problems• Can the soils and rocks properly

support the construction project?

(from La Torre di Pisa, 2001)(from Norwegian Geotechnical Institute, 2000)

Geotechnical Engineering Problems

• How will the groundwater conditions impact the engineering project?

Teton Dam Failure (1975)

(from The Teton Dam Flood 2001)

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Geotechnical Engineering Problems• How will the groundwater conditions impact the

engineering project?Teton Dam Failure (1975)(cont.)

(from The Teton Dam Flood 2001)

Geotechnical Engineering Problems• How will the groundwater conditions impact the

engineering project?Teton Dam Failure (1975)(cont.)

11 to 14 people died during this failure…

(from The Teton Dam Flood 2001)

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Geotechnical Engineering Problems• What will be the impact of excavations, grading,

or filling?

(from BECC Engineering 2001)

Hong Kong:

(Hong Kong Slope Safety 2001)

Geotechnical Engineering Problems

• Are natural or proposed earth slope stable?

(from Norwegian Geotechnical Institute, 2001)

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Geotechnical Design

• Designis the process whereby a problem is solved for certain conditions and constrains, and meeting specified performance criteria.

• This definition applies to any civil and geological engineering system.

Foundation Systems• Designing of Shallow Foundation Systems –

Differential Settlements

“Kissing Silos”

(from Sharma 2003)

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Foundation Systems

• Designing of Shallow Foundations Systems –Bearing Capacity Failure

(from Budhu 2000)

TransconaGrain Elevator

Foundation SystemsDeep Foundation Systems: Driven Piles

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Foundation Systems

Deep Foundation Systems: Drilled Shafts

Earth Pressure and Retaining Walls

• Designing of retaining wallsReinforced Earth

(from BECC Engineering 2001)

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Earth Pressure and Retaining Walls• Reinforced Earth Walls

(The Reinforced Wall Company 2003)

Earth Pressure and Retaining Walls• Sheet Piles

(Boulanger and Duncan 2003)

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Retaining Structure Systems

• Gabions

(Gabions LEMAC (2003)

Retaining Structure Systems

• Tie-backs

(Boulanger and Duncan 2003)

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Retaining Structure Systems

• Excavation Support Systems

(Boulanger and Duncan 2003)

Soil Improvement

• Stone Columns

(Boulanger and Duncan 2003)

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Soil Improvement

• Jet Grouting

(Boulanger and Duncan 2003)

Soil Improvement

• Compaction Grouting

(Boulanger and Duncan 2003)

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Soil Improvement

• Chemical Injection

(Boulanger and Duncan 2003)

Geotechnical Earthquake Engineering• Effects of earthquakes

1964 Niigata Earthquake 1967 Caracas Earthquake

(from Kramer –www.ce.washington.edu 1996)

(from Alshibli 2001)

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Geotechnical Earthquake Engineering• Effects of earthquakes

1995 Kobe Earthquake 1999 Chi Chi Earthquake

(Boulanger and Duncan 2006)

Geosynthetics

• Geosynthetic stabilized walls

(Environmental Science & Engineering 2007)(kshitija.wordpress.com 2007)

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Geoenvironmental Engineering

• Characterization and remediation of Geo-environmental hazards

(from Willmer 2001)

MSW Landfill

(from Norwegian Geotechnical Institute 2001)

Some Suggestions

Attend the lectures.

Develop a good feel for the subject.

It takes longer to understand from the lecture notes

It takes longer to understand from the lecture notes

It is practical, interesting and makes lot of sense.

It is practical, interesting and makes lot of sense.

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Some Suggestions…

Work in groups!!.

Some Suggestions…

Thou shall not wait till the last minute!!.

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Exams

My mama always said, “Exam is like a box of chocolates; you never know what you gonna get”

Recipe for Success

I like soils… I like soils….I like soils….

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Bibliography• Hong Kong Slope Safety (2001). Company Web Site.

http://hkss.ced.gov.hk/hkss/eng/index.htm• Norwegian Geotechnical Institute (2001). Institute Web Site.

http://www.ngi.no/english/default.htm• Praad Geotechnical, Inc. Consulting Engineers (2001). Company Web Site.

http://www.praad.com/• BECC, Inc. (2001). Company Web Site. http://beccinc.com/geotechnical.htm• Willmer Engineering, Inc. (2000). Company Web Site.

http://www.willmerengineering.com/• Coduto, D. (1999). Geotechnical Engineering. Principles and Practice. Prentice-Hall. • La Torre di Pisa (2001). Official Web Site. http://torre.duomo.pisa.it/• The Leaning Tower (2001). Web Site. http://www.cisiau.unipi.it/~pierotti/Torre/• The Teton Dam Flood (2000). Web Site.

http://www.ida.net/users/elaine/idgenweb/flood.htm• McCarthy, D. (1998). Essential of Soil Mechanics and Foundation. Prentice-Hall.• Kramer, S. (1996). Geotechnical Earthquake Engineering. Prentice-Hall.• Budhu, M. (2000). Soil Mechanics and Foundations. Wiley.