GEOTECHNICAL ENGINEERING (SY (SE) Degree Course in Civil Engineering Semester 2)

233 Pages·2021·8.63 MB·English

by  Dr. R.R. Sorate V.R. Phadke , Mrs. S.S. Jain , Dr. R.K. Jain

A TEXT BOOK OF

GGEEOOTTEECCHHNNIICCAALL EENNGGIINNEEEERRIINNGG

FOR
SEMESTER – II

SSEECCOONNDD YYEEAARR DDEEGGRREEEE CCOOUURRSSEE IINN CCIIVVIILL EENNGGIINNEEEERRIINNGG

Strictly According to New Revised Credit System Syllabus of
Savitribai Phule Pune University
(w.e.f. June 2020-2021)

V. R. PHADKE Dr. R. K. JAIN

M.E. (Civil) M.E. (Civil), Ph.D.
Formerly Professor Civil Engg. Dept., Principal,
Rajashri Shahu College of Engineering, Rajashri Shahu College of Engineering,
Tathawade, Pune . Tathawade, Pune.

Mrs. S. S. JAIN Dr. R. R. SORATE
M.E. (Civil) M.Tech (Geotech.) Ph.D.
Asst. Prof., Civil Engg. Dept., Asso. Prof. & Head, Civil Engg. Dept.,
Sinhgad College of Engineering, TSSM’s PVPIT,
Vadgaon (Bk), Pune. Bavdhan, Pune.

N5681
GEOTECHNICAL ENGINEERING (SE CIVIL) ISBN : 978-93-90596-59-1
First Edition : January 2021
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PREFACE
It gives us great pleasure to present the book 'Geotechnical Engineering’ for the students of Second Year Degree
Course in Civil Engineering of the Savitribai Phule Pune University. This book is strictly as per the New Revised Credit
System Syllabus 2019 Pattern with effect from the Academic Year 2020-2021.
As per New Revised Examination Scheme which has been implemented from this academic year, In-Semester
assessment carries 30 marks over first two units and End-Semester Examination carries 70 marks on the remaining
units 3, 4, 5 and 6.
The Theory Course will have 3 Credits.
The book is written such that all the basic concepts are explained in a simplified manner. It is presented in a more
conceptual manner rather than mathematical, as required by the new examination system. It is our objective to keep the
presentation systematic, consistent, intensive and clear, through explanatory notes and figures.
Main feature of this book is Complete Coverage of the New Credit System Syllabus with large number of
Solved Examples, Exercises, Model Question Papers of In-Sem. and End Sem. Exams.
We are sure that this book will cater to all needs of students for this subject.
We also take this opportunity to express our sincere thanks to Shri. Dineshbhai Furia, Shri. Jignesh Furia,
Mrs. Nirali Verma and entire team of Nirali Prakashan, namely Mrs. Deepali Lachake (Co-ordinator), who really have taken
keen interest and untiring efforts in publishing this text.
We would like to make a special mention of the valuable contribution made by late Shri M. P. Munde in his continuous
efforts during the last two decades, in making the text popular among students and teachers. Without his perseverance
and zeal, successive editions would not have been possible.
The advice and suggestions of our esteemed readers to improve the text are most welcome and will be highly
appreciated.

Pune Authors

SYLLABUS

Unit I : Introduction and Index Properties (06 Hours)
(a) Introduction to Geotechnical Engineering and its applications to Civil Engineering. (Types of soil structure, major soil
deposits of India), Field identification of soils. {Introduction to soil exploration: objective and purpose.}
(b) Three phase soil System weight – Volume relationships, Index properties of soil: Methods of determination and their
significance. [IS and Unified Soil classification systems.]
Unit II : Permeability and Seepage (06 Hours)
(a) Soil water, Permeability definition and necessity of its study, Darcy’s law, Factors affecting permeability. (Laboratory
measurement of permeability: Constant head method and Falling head method as per IS 2720.) {Field test for
determination of permeability- Pumping in test and Pumping out test as per IS 5529 Part-I.}Permeability of stratified
soil deposits.
(b) Seepage and Seepage Pressure, Quick sand phenomenon, Critical hydraulic gradient, General flow equation for 2-D
flow (Laplace equation). [Flow Net, properties and application] Flow Net construction for flow under sheet pile and
earthen dam.
Unit III : Compaction and Stress Distribution (06 Hours)
(a) Compaction – Introduction, Comparison between compaction and consolidation.[Compaction tests- Standard Proctor
test, Modified Proctor test]. Zero air void line. Factors affecting compaction. Effect of compaction on soil properties.
(Field compaction methods and compaction equipment for different types of soil), Placement water content, Field
compaction control- Use of compaction test result. {Proctor needle in field compaction control.}
(b) Stress Distribution in Soils – Geostatic stress, Boussinesq’s theory with assumptions for point load and circular load
(with numerical), Pressure Distribution diagram on a horizontal and vertical plane, Pressure bulb and its significance.
Westergaard’s theory, Equivalent point load method. Approximate stress distribution method.
Unit IV : Shear Strength of Soil (06 Hours)
(a) Introduction – Shear strength an Engineering Property. Mohr’s stress circle, Mohr- Coulomb failure theory. The
effective stress principle- Total stress, Effective stress and Neutral stress / pore water pressure. [Peak and Residual shear
strength], {factors affecting shear strength.} (Stress-strain behaviour of sands and clays.)
(b) Measurement of Shear Strength – Direct Shear test, Triaxial Compression test, Unconfined Compression test, Vane
Shear test. Their suitability for different types of soils, advantages and disadvantages. Different drainage conditions for
shear tests. (Sensitivity and thixotropi of cohesive soils.)
Unit V : Earth Pressure (06 Hours)
(a) Earth Pressure – Introduction, Rankine’s state of Plastic Equilibrium in soils- Active and Passive states due to wall
movement, Earth Pressure at rest. [Rankine’s Theory: Earth pressure on Retaining wall due to submerged backfill.]
(b) Backfill with uniform surcharge, Backfill with sloping surface, Layered backfill. (Coulomb’s Wedge theory. Rebhann’s
and Culmann’s graphical method of determination of earth pressure.)
Unit VI : Stability of Slopes (06 Hours)
(a) Stability of Slopes – Classification of slopes and their modes of failure, Stability of slope: (i) Taylor’s stability number,
(ii) Swedish slip circle method, (iii) Friction circle method, (iv) Bishop’s method. (Infinite Slopes in cohesive and cohesion
less soil,) {Landslides- Causes and remedial measures.}
CONTENTS
UNIT I - INTRODUCTION AND INDEX PROPERTIES
Chapter 1 : Introduction 1.1-1.2
1.1 Soil 1.1
1.2 Soil Mechanics 1.1
1.3 Soil Engineering or Geotechnical Engineering 1.1
1.4 Complexity of Soil 1.1
1.5 Comparison of Soil with Other Materials 1.2
• Exercise 1.2
Chapter 2 : Soil as Engineering Material 2.1-2.24
2.1 Origin of Soil 2.1
2.2 Types of Rocks and Geological Cycle 2.1
2.3 Principal Soil Types 2.1
2.3.1 Residual and Transported Soils 2.2
2.4 Soil Structure 2.3
2.4.1 Single Grained Structure 2.3
2.4.2 Honeycomb Structure 2.3
2.4.3 Flocculent Structure 2.4
2.4.4 Dispersed Structure 2.4
2.4.5 Composite Soil Structures 2.4
2.5 Soil Deposits of India 2.4
2.6 Field Identification Test of Soil 2.6
2.6.1 Coarse Grained Soil 2.6
2.6.2 Fine Grained Soil 2.6
2.7 Introduction to Soil Exploration 2.7
2.7.1 Soil Exploration and Site Investigation 2.7
2.7.2 Steps in Soil Exploration 2.8
2.7.3 Planning the Ground Investigation Program 2.8
2.7.4 Methods of Obtaining Soil Samples 2.9
2.8 Geotechnical Problems 2.12
2.9 Three Phase System of Soil 2.13
2.10 Basic Definitions 2.14
2.11 Inter-Relationships 2.15
• Summary 2.22
• Exercise 2.22
• Solved University Questions and Numericals 2.23
Chapter 3 : Geotechnical Properties 3.1-3.42
3.1 Nature of Soil 3.1
3.2 Properties of Soils 3.2
3.2.1 Engineering Properties 3.2
3.2.2 Index Properties 3.3
3.3 Specific Gravity Determination 3.3
3.4 Water Content Determination 3.4
3.5 Field Density (Unit Weight) Determination 3.8
3.6 Consistency and Consistency Limits 3.10
3.6.1 Determination of Consistency Limits 3.11
3.6.2 Consistency Indices 3.16
3.7 Mechanical Analysis (Size Gradation Analysis) 3.18
3.7.1 Sieve Analysis 3.18
3.7.2 Sedimentation Analysis 3.19
3.8 Grading of Soil 3.23
3.9 Soil Identification and Classification 3.24
3.9.1 Particle Size Classification 3.24
3.9.2 Unified Soil Classification and Indian Standard Classification 3.25
3.9.3 Boundary Classification 3.26
3.9.4 Field Tests for Soil Classification 3.26
3.9.5 Difference between Sand and Clay 3.27
• Summary 3.40
• Exercise 3.41
• Solved University Questions and Numericals 3.42
UNIT II - PERMEABILITY AND SEEPAGE
Chapter 4 : Permeability and Seepage 4.1-4.30
4.1 Introduction 4.1
4.2 Soil Water 4.1
4.3 Surface Tension 4.1
4.4 Capillary Water 4.1
4.5 Capillary Rise in Soils 4.2
4.6 Frost Heave 4.3
4.7 Frost Boil 4.3
4.8 Soil Suction 4.3
4.9 Bulking of Sand 4.3
4.10 Slaking of Clay 4.4
4.11 Shrinkage and Swelling 4.4
4.12 Permeability 4.4
4.13 Darcy's Law 4.4
4.14 Validity of Darcy's Law 4.5
4.15 Determination of Coefficient of Permeability 4.5
4.16 Seepage Velocity and Discharge Velocity 4.7
4.17 Factors Affecting the Permeability 4.7
4.18 Permeability of Stratified Soil Deposits 4.8
4.19 Seepage Pressure 4.8
4.20 Quick Sand Condition or Critical Hydraulic Gradient 4.9
4.21 Laplace's Equation 4.9
4.22 Solution of Laplace Equation – Flow Net 4.10
4.22.1 Properties of Flow Net 4.11
4.22.2 Construction of Flow Net 4.11
4.23 Graphical Method 4.11
4.24 Examples of Constructing Flow Nets 4.12
4.24.1 Sheet Pile 4.12
4.24.2 Homogeneous Earthen Dam 4.13
4.25 Construction of Top Seepage Line of Earth Dam 4.13
4.26 Uses of Flow Net 4.14
4.27 Piping 4.15
4.28 Design of Filters 4.15
4.29 Field Permeability 4.16
4.29.1 Some Definitions 4.16
4.30 Field Determination of 'k' 4.16
4.30.1 Pumping-Out Test 4.16
4.30.2 Pumping-In Tests 4.18
• Summary 4.17
• Exercise 4.28
• Solved University Questions and Numericals 4.29
UNIT III - COMPACTION AND STRESS DISTRIBUTION
Chapter 5 : Compaction 5.1-5.18
5.1 Introduction 5.1
5.2 Mechanics of Compaction 5.1
5.3 Difference between Compaction and Consolidation 5.2
5.4 Factors Affecting Compaction 5.2
5.5 Compaction Tests (Laboratory Test) 5.3
5.5.1 Standard Proctor Compaction Test 5.3
5.5.2 Heavy Compaction Test or Modified Proctor Test 5.4
5.5.3 Moisture Content – Dry Density Relationship (Standard Proctor Compaction Test) 5.4
5.5.4 Correction for Oversize Fraction 5.5
5.5.5 Comparison Between Light Compaction and Heavy Compaction 5.5
5.5.6 Zero Air Voids or Saturation Curve 5.6
5.5.7 Optimum Moisture Content (OMC) 5.6
5.6 Effect of Compaction On Soil Properties 5.6
5.7 Field Compaction 5.8
5.7.1 Placement Water Content 5.8
5.7.2 Field Compaction Control 5.8
5.7.3 Compacting Equipments 5.9
• Summary 5.17
• Exercise 5.17
• Solved University Questions and Numericals 5.17
Chapter 6 : Stress Distribution in Soils 6.1-6.20
6.1 Introduction 6.1
6.2 Geostatic Stresses 6.1
6.3 Elastic Solutions 6.2
6.3.1 Stresses Due to Point Load 6.2
6.3.2 Pressure Distribution Diagrams 6.2
6.3.3 Stresses Due to the Load Uniformly Distributed Over a Circular Area 6.3
6.3.4 Stresses Due to Line Load 6.4
6.3.5 Strip Area Carrying Uniform Pressure 6.4
6.3.6 Stresses Due to Equivalent Load 6.5
6.4 Westergaard’s Theory 6.5
6.5 Comparison of Boussinesq’s & Westergaard’s Equations 6.6
6.6 Stress Isobar or Pressure Bulb Concept 6.6
6.7 Approximate Methods 6.7
• Summary 6.18
• Exercise 6.18
• Solved University Questions and Numericals 6.19
UNIT IV - SHEAR STRENGTH OF SOIL

Chapter 7 : Shear Strength Of Soil 7.1-7.46
7.1 Shear Stress in Soil 7.1
7.2 Effective Stress and Pore Water Pressure 7.1
7.2.1 Effective Stress Concept 7.2
7.2.2 Effective Stress in Dry or Drained Condition 7.3
7.2.3 Importance of Effective Stress Concept 7.3
7.3 Stress–Strain Curve 7.3
7.3.1 Stress-Strain Relations in Soils and Rocks 7.4
7.3.2 Determination of Soil Modulus 7.4
7.4 Principal Planes 7.5
7.5 Mohr's circle 7.6
7.5.1 Plotting of Mohr's Circle 7.7
7.5.2 Location of Pole in Mohr's Circle 7.8
7.5.3 Features of Mohr's Circle 7.8
7.6 Mohr–Coulomb Failure Theory 7.8
7.6.1 Limitations of Mohr–Coulomb Theory 7.9
7.7 Alternate Representation of Strength Parameters 7.9
7.7.1 Failure Plane and Plane of Maximum Shear Stress 7.10
7.8 Measurement of Shear Strength 7.10
7.8.1 Different Drainage Conditions 7.11
7.8.2 Mode of Application of Shear Force 7.11
7.9 Direct Shear Test 7.11
7.10 Triaxial Compression Test 7.13
7.11 Unconfined Compression Test 7.17
7.12 Vane Shear Test 7.18
7.13 Factors Affecting the Shear Strength 7.20
7.14 Skemptons Pore Pressure Parameters 7.20
7.15 Ultimate Strength and Residual Strength 7.21
7.16 Thixotropy 7.21
7.17 Sensitivity 7.21
• Summary 7.42
• Exercise 7.43
• Solved University Questions and Numericals 7.44

UNIT V - EARTH PRESSURE
Chapter 8 : Earth Pressure 8.1-8.22
8.1 Earth Pressure 8.1
8.2 Limit Analysis and Limit Equilibrium 8.1
8.2.1 Definition 8.1
8.2.2 Basic Elements 8.1