Foundation engineering lecture 1

FOUNDATION ENGINEERING

BCE III/I

Anand PantaBE(Civil), MS (Geomechanics)

Lecturer and Deputy Head

Department of Civil Engineering

Kantipur Engineering College

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FOUNDATION ENGINEERINGOBJECTIVES: To be familiar with the basic concepts and tools used

to determine structure/ foundation/ soil interactions Analyze the behavior of geotechnical structures

under static loads, this includes: Soil Exploration Shallow Foundation Deep Foundation Retaining structures <<Gravity walls>> Retaining structures <<Flexible walls>> Soil arching Soil improvements

Determine the behavior involved in these structures Present the design methods

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WHAT ARE THE GEOTECHNICAL STRUCTURES?o Foundations

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RETAINING STRUCTURESo Gravity walls

Gabion wall

Concrete wallReinforced concrete walls

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Sheet pile walls

Coffer dam

RETAINING STRUCTURES

o Flexible Walls

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GENERAL OUTLINE

Marks distribution

Full Marks(125)

Theory(100)

Final(80)

Internal (20)

Practical(25)

Final (80) Final examination by IOEInternal (20) Attendance & Tutorials(20%)+Class Test (30%)+ Assessment II(50%)Practical (25) Report (Observation Tour of a site investigation project)+Objective test

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GENERAL OUTLINE: SYLLABUS

Syllabus

Chapter Title Lecture

Hours

Marks

1 Introduction 1 2

2 Soil Exploration 6 12

3 Lateral Earth Pressure Theories and Retaining Walls

10 16

4 Arching in Soils and Braced Cuts 3 4

5 Flexible Retaining Structures and Coffer Dams

3 4

6 Bearing Capacity and Settlement of Shallow Foundation

6 12

7 Mat Foundations 3 6

8 Pile Foundations 6 12

9 Well Foundations 4 8

10 Foundation Soil Improvements 3 4

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GENERAL OUTLINE

Reference Books1. “Foundation Analysis and Design” Joseph E.Bowels. McGraw-Hill International

Editions, Fifth Edition, 1997

2. “Principles of Foundation Engineering” Braja M. Das, Fifth Edition, 2003.

3. “Basic and Applied Soil Mechanics” Gopal Ranjan and ASR Rao, Second Edition New Age International Publishers, 2000

4. “Soil Mechanics and Foundation Engineering” K.R. Arora Standard Publisher Distribution 1997

5. “A Text Book of Soil Mechanics and Foundation Engineering in SI units” VNS Murthy UBS Publishers Distributors Ltd. Fourth Edition 1993

6. “Pile Foundation Analysis and Design”, H.G. Poulos and E.H. Davis, John and sons 1980

7. “A Text Book of Foundation Engineering” Dr. R.K. Poudel and R. Neupane.

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CHAPTER 1 INTRODUCTION1.1 Foundation Engineering, Importance and purpose Foundation

Substructure elements, used to transfer the load of a structure(self weight +other actions) to the soil

Correspond to either limited loads or good quality soil (strength and stiffness)

Different geometries

Reinforced concrete

Two main aspect of the behavior: Ultimate limit failure: bearing capacity Serviceability limit: settlement

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WHY FOUNDATION ENGINEERING IS IMPORTANT?

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Pile failure due to earthquake

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DIFFERENTIAL SETTLEMENT

The Leaning Tower of Pisa leans due to a faulty foundation.

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1.2 CLASSIFICATION AND GENERAL REQUIREMENT

Classification

Foundation

Shallow

Spread or Isolated Footing

Strip or wall Footing

Combined Footing Strap Footing Mat

foundation

Deep

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CLASSIFICATION

Strap

W

•Terzaghi(1943)If D/B<1, shallow•If D/B>1 & <15, moderately deep•If D/B>15, deep Foundation

Strip Footing (L>>B)

Strap footing Raft foundation

Isolated footing

o Shallow Foundation

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DEEP FOUNDATION

Pile Foundation

End bearing pile Friction pile

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GENERAL REQUIREMENT

Location and depth criteria

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SETTLEMENT CRITERIA

Differential settlement Example: Leaning Tower Of

Pisa non-uniform, sponge-like

saturated clay soil

The Leaning Tower of Pisaleans due to a faulty foundation.

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SETTLEMENT CRITERIA

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SETTLEMENT CRITERIA

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Shear failure criteria or bearing capacity criteria

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1.3 FACTORS INFLUENCING THE CHOICE OF FOUNDATION

Principal Factors:• Function of structure• Load on foundation• Subsurface condition• Cost

Other factors:• Need of client or owner• Type of super structure• Environmental considerations• Margin of safety• Risk Level• Service life

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1.4 SELECTION OF FOUNDATION TYPE

Steps to select a foundation1. Obtain information concerning the nature of the

super-structure and loads to be transmitted2. Determine the subsurface condition3. Engineering judgment for suitable type of

foundation4. Detailed study and tentative design of most

promising types of foundation5. Prepare cost estimate of each promising type

and choose best with respect to performance and cost

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SAMPLE QUESTIONS

Describe with sketches the various types of shallow foundations. Explain under what circumstances they are used.

Describe various factors that affect foundation selection. Explain the step by step procedure for the selection of a suitable in a given situation.

What are the fundamental requirements of foundation selection?

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Thank you for your attention!