Geotechnical and Foundation Engineering By Dr. A. K. Verma, Rahul Verma

CHAPTER 8 STRESS DISTRIBUTION IN
SOILS DUE TO SURFACE LOADS

8-1. Introduction
8-2. Boussinesq’s Equation
8-3. Vertical Stress Distribution Diagram
(1) Vertical stress isobar diagram
(2) Vertical stress distribution on a horizontal plane (Fig. 8-2)
(3) Vertical stress distribution on a vertical line (Fig. 8-2)
8-4. Vertical Stress Beneath Loaded Areas
(1) Line load
(2) Strip load
(3) Uniformly loaded circular area
(4) Uniformly loaded rectangular area
(5) Long embankment loading
(6) Uniform load on an annular area (Ring foundation)
8-5. Influence Chart (Newmark’s Chart)
8-6. Approximate Stress Distribution Methods for Loaded Area
(1) Equivalent point load method
(2) Two to one method
8-7. Westergaard’s Equation
8-8. Typical examples of Vertical stresses below applied loads
8-9. Contact Pressure
8-10. Typical example on stress distribution in soils due to surface loads
Exercises 8

CHAPTER 9 SOIL COMPACTION

9-1. Introduction
9-2. Laboratory tests
9-3. Factors AFFECTING compaction
(1) Water content
(2) Type of soil
(3) Method of compaction
(4) Compactive effort
(5) Use of admixture
9-4. Structure and engineering behaviour of compacted cohesive soils
(1) Structure
(2) Permeability
(3) Compressibility
(4) Swelling
(5) Shrinkage
(6) Stress-strain relationship
(7) Pore water pressure
9-5. Compaction in the Field
9-6. Compaction Specifications and Field Control
9-7. Typical examples of soil compaction
Exercises 9

CHAPTER 10 SHEAR STRENGTH OF SOILS

10-1. Introduction
10-2. Stress At point – mohr’s circle of stress
10-3. Mechanism of shear resistance
10-4. Mohr-coulomb’s failure criterion
(1) Concept of failure in soils
(2) Mohr’s failure criterion and Mohr’s failure hypothesis
(3) Coulomb’s equation and Mohr-Coulomb’s criterion
10-5. Measurement of shear strength
(1) Direct shear test
(2) Triaxial Test
(3) Unconfined compression test
(4) Vane shear test
(5) Special shear test
10-6. Shear strength of clayey soils
(1) Untrained strength from UU Test
(2) Consolidated undrained strength from CU test
(3) Consolidated drained strength test
(4) Shear strength – a unique function of effective stress
(5) Comparison of the results of CU and CD tests
(6) Stress-strain and volume change relationships
(7) Effect of strain rate

10-7. Shear strength of sands
(1) Behaviour of saturated sands under undrained conditions
(2) Factor affecting angle of shearing resistance
(3) Angle of repose
(4) Effect of moisture
(5) Effect of intermediate principal stress
10-8. Drainage conditions and strength parameters
10-9. Stress paths
10-10. Pore pressure parameters
10-11. Elastic properties of soil
(1) Modulus of elasticity
(2) Poisson’s ratio, m
(3) Shear modulus, G
10-12. Typical Examples of shear strength of soils
Exercises 10

CHAPTER 11 ARCHING IN SOILS AND BRACED CUTS

11-2. Cain’s theory
11-3. Tunnels through sand
11-4. Braced excavations
11-5. Earth pressure against bracing in cuts
11-6. Heave of the bottom of cut in soft clays
11-7. Strut loads
11-8. Deep cuts — apparent earth pressure diagram
11-9. Typical examples of Vertical stresses below applied loads
Exercises 11

CHAPTER 12 LATERAL EARTH PRESSURE

12-1. Introduction
12-2. Types of lateral earth pressure
12-3. Earth pressure at rest
12-4. Earth pressure theories
12-5. Rankine’s theory
12-5-1. Plastic equilibrium of soil — Active andpassive rankine states
12-5-2. Active earth pressure of cohesionless soil
12-5-3. Passive earth pressure of cohesionless soil
12-6. Coulomb’s earth pressure theory or coulomb’s Wedge theory
12-6-1. Active state
12-6-2. Passive state
12-7. Culmann’s graphical method for
active pressure for cohesionless soil
12-8. Rebhann’s graphical method for active thrust
12-9. Active earth pressure of cohesive soils (Rankine’s theory)
12-10. Passive earth pressure: Rankine’s theory
(1) Cohesionless backfill
(2) Cohesive backfill
(3) Sloping backfill
12-11. Typical problems of lateral earth pressure
Exercises 12

CHAPTER 13 STABILITY OF SLOPES

13-1. Introduction
13-2. Stability analysis of infinite slopes in sand (Cohesionless soil)
13-3. Stability Analysis of Infinite slopes made of clay
13-4. Factor of safety
13-5. Stability Analysis of Finite slopes
13-6. The Swedish slip circle method (Fig. 13-8)
(1) fu = 0° analysis
(2) c-f analysis or method of slices
13-7. Method of locating critical slip circle (Fig. 13-12)
13-8. Stability of
side slopes of Earth dam
(1) Stability of down stream slope during steady seepage
(2) Stability of up stream slope during sudden draw down
(3) Stability of slopes immediately after construction
13-9. Friction circle method
13-10. Stability Analysis of a finite slope using Taylor stability
number
13-11. Bishop’s method of stability analysis
13-12. Typical examples of stability of slope (S.O.S.)
Exercises 13

CHAPTER 14 COMPRESSIBILITY OF
SOILS AND CONSOLIDATION

14-1. Introduction
14-2. The consolidation process: spring analogy
14-3. Consolidation of laterally confined soil
(1) Skempton (1944)
(2) Houge (1957)
14-4. Consolidation settlements, Sc
14-5. Soil condition with regard to its consolidation
(1) Normally consolidated (N.C.) soils
(2) Over consolidated/pre-consolidated (O.C.) soils
(3) Under consolidated (U.C.) soils
14-6. Determination of pre-consolidation or
over consolidation pressure, s¢p
14-7. Terzaghi’s theory of one-dimensional consolidation
14-8. Solution of the consolidation equation
14-9. Laboratory one dimensional consolidation test
14-10. Calculation of void ratio
14-10-1.Height of solid method
14-10-2.Change in void ratio method (Table 14-5)
14-11. Coefficient of volume change (mv)
14-12. Compression index (Cc)
14-13. Determination of coefficient of consolidation (Cv)
14-13-1.Square root of time fitting method
14-13-2.Logarithm of time fitting method
14-14. Determination of coefficient of permeability (k)
14-15. Secondary consolidation
14-16. Typical solved examples of compressibility of
soils and consolidation
Exercises 14

CHAPTER 15 SHALLOW FOUNDATIONS AND
BEARING CAPACITY

BEARING CAPACITY
15-1. Introduction
(1) Strip footing or continuous footing
(2) Spread footing
(3) Raft or mat foundation
15-2. General requirement of foundations
(1) Shear failure criterion
(2) Settlement criterion
(3) Location and depth criterion
15-3. Terminology
15-4. Allowable Bearing Pressure for Safe Design
15-5. Bearing Capacity of Shallow Foundations
(1) General shear failure (GSF)
(2) Local shear failure (LSF)
(3) Punching shear failure (PSF)
15-6. Terzaghi’s Bearing Capacity Theory
(1) Assumptions
(2) Local shear failure
(3) Effect of shapes
(4) Effect of water-table
(5) Skempton’s bearing capacity analysis for clayey soils
(6) Meyerhof’s analysis
(7) Hansen’s recommendations
(8) Vesic’s bearing capacity factor
(9) IS code recommendation for bearing capacity
(10) Two layered system
(11) Desiccated soil
(12) Bearing capacity of cohesionless soils based on
standard penetration test
For strip footings
For square and circular footings
(13) Bearing capacity of cohesionless soils from
static cone resistance
(14) Bearing capacity of footings on layered soils
(15) Factors affecting bearing capacity
(16) Presumptive bearing capacity
15-7. Settlement of Shallow Foundations
(1) Components of settlement
(2) Immediate or elastic settlement

Corrections to settlement due to consolidation
(3) Seat of settlement
(4) Settlement of foundations on granular soils
(5) Method based on static cone penetration test
(6) Allowable settlement
15-8. Allowable Bearing Pressure
(1) Granular soils
(2) Cohesive soils
15-9. Steps Involved in
Proportioning of Footings
15-10. Typical Examples on
Shallow Foundations and Bearing Capacity
Exercises 15

CHAPTER 16 PILE FOUNDATION

16-1. Introduction
16-2. Load transfer mechanism
16-3. Types of pile
16-3-1. Classification based on material and composition
16-3-2. Classification based on method of installation
(1) Driven piles
(2) Cast-in-situ piles
(3) Driven and Cast-in-situ piles
16-3-3. Classification based on
load transfer mechanism
(1) End-bearing piles
(2) Friction piles
(3) Tension or uplift piles
(4) Compaction piles
(5) Anchor piles
16-4. Piles subjected to vertical loads
16-4-1. Pile load carrying capacity based on static formula
(2) For non cohesive soil
Piles in stratified soil
16-4-2. Pile load carrying capacity based on
Dynamic formulae
(1) Engineering news formula
(2) Hiley’s formula
16-4-3. Pile loadss carrying capacity based on penetration test data
16-4-3-1. Pile load carrying capacity based on
standard penetration test N
(1) Piles in granular soils
(2) Piles in cohesive soils
16-4-3-2. Pile capacity based on static cone penetration test (SCPT)
or cone penetration test (CPT)
(1) Van Der Veen’s method for piles in cohesionless soil (1957)
(2) Schmertmann’s method for cohesionless and cohesive soils
16-4-4. Pile load test
16-5. Group action in piles
16-5-1. Efficiency of the pile group
16-5-2. Design of Pile Groups Pile group in cohesive soil bed
16-6. Negative skin friction
16-7. Settlement of pile and pile group
(1) Settlement of single pile embedded in sand
(2) Settlement of single pile embedded in clay
(3) Settlement of pile group is sand
(4) Settlement of pile groups in clay
16-8. Typical examples on pile foundation
16-8-1. Examples based on static formulae
16-8-2. Example based on dynamic formulae
16-8-3. Example based on penetration test data
16-9. Laterally loaded piles
16-10. Laterally loaded long piles embedded in cohesive soils
16-11. Ultimate lateral load analysis:
Broms’ method
(1) Short pile (embedded in sand) [Fig. 16-30(a)]
(2) Short Pile (embedded in clay) [Fig. 16-30(b)]
(3) Long pile in sand or clay
(2) Check for pile head defection
16-12. Allowable Lateral deflection of a pile

16-13. IS Code Method:
Lateral load carrying capacity of a pile
(1) For sand and normally consolidated clays
(2) For Preloaded clays or
over consolidated clays with constant soil modulus
(3) Calculation of deflection and moment in a long elastic pile
(4) Calculation of moment
16-14. Under-Reamed Pile
16-15. Load test on Under-reamed piles
16-16. Cyclic pile load test
16-17. Difference In Fixed Head And Free Head Pile
Exercises 16

CHAPTER 17 WELL FOUNDATIONS

17-1. Introduction
17-2. Various Types of Wells or Caissons
(1) Open caissons or well
(2) Box caissons
(3) Pneumatic caissons
17-3. Components of a Well Foundation
(1) Well-cap (5) Bottom plug
(2) Steining (6) Dredge hole
(3) Curb (7) Top plug
(4) Cutting edge
17-4. Requirement of Shapes of Wells
17-5. Depth of A Well Foundation
(1) Minimum grip length below the scour depth
(2) Base pressure within permissible limits
17-6. Forces Acting on a Well
17-7. Lateral Stability of Well Foundation
(1) Terzaghi’s analysis
(2) IRC method
(3) Elastic theory method
(4) Conditions of stability
(5) Ultimate soil resistance method
Base resisting moment, Mb
Side resisting moment, Ms
Friction resisting moment, Mf
17-8. Lateral Stability of a Heavy well
17-9. Sinking of a Well
(1) Controlled dredging
(2) Eccentric loading
(3) Pulling the well
(4) Pushing the well
(5) Water jetting and/or digging pit on the higher side
(6) Obstacles below the cutting edge and loading
17-10. Bearing capacity of a well
Exercises 17

CHAPTER 18 FLEXIBLE RETAINING STRUCTURES AND
COFFERDAMS

18-1. Introduction
18-2. Cantilever sheet pile wall
18-2-1. Cantilever sheet pile in granular soil Assumption
18-2-2. Cantilever sheet pile in
Granular soils — An Approximate Analysis
18-2-3. Cantilever sheet pile in cohesive soil ( fu = 0 Condition)
18-3. Anchored bulkhead
18-3-1. Free-earth support method
18-3-2. Fixed earth support method
Fixed earth support method for
designing the anchored bulkheads
18-4. Cofferdams
(1) Earth embankments
(2) Cantilever sheet pile
(3) Double wall cofferdams [Fig. 18-8(c)]
(4) Braced cofferdams
(5) Cellular cofferdams [Fig. 18-8(e)]
18-5. Typical Examples on flexible
retaining structures and cofferdams
Exercises 18

CHAPTER 19 GEOSYNTHETICS: APPLICATION AND DESIGN

19-1. Introduction
19-2. Types of Geosynthetic materials
19-2-1. Geotextile (GT)
(1) Woven geotextiles
(2) Nonwoven geotextiles
19-2-2. Geogrid (GG)
(1) Integral junction geogrids
(2) Fused junction geogrids
(3) Woven junction geogrids
19-2-3. Geonets (GN)
19-2-4. Geomembrane (GM)
19-2-5. Geosynthetic clay liner (GCL)
19-2-6. Geofoam 487
19-2-7. Geocell 487
19-2-8. Geocomposites
19-3. Geosynthetics functions
(1) Separation
(2) Reinforcement
(3) Filtration488
(4) Drainage 488
(5) Moisture barrier/containment
(6) Protection
(7) Stiffening
19-4. Application of geosynthetics and
controlling functions
19-5. Testing and evaluation of geosynthetics
19-6. Geosynthetic properties and
parameters
(1) Physical properties of geosynthetics
(2) Mechanical properties of geosynthetics
19-7. Reinforced earth wall (R.E. wall)
19-7-1. Advantages of R.E. walls
19-7-2. Analysis and Design of R.E. walls
Exercises 19

CHAPTER 20 LABORATORY EXPERIMENTS AND
FIELD EQUIPMENT

20-1. Laboratory experiments
20-2. Field Equipment used in
geotechnical practices
(1) Tipper trucks (Fig. 20-2)
(2) Dump trucks (Fig. 20-3 and fig. 20-4)
(3) Concrete trucks/Transit mixers (Fig. 20-5)
(4) Crawler cranes for pile driving work
(Fig. 20-6, fig. 20-7 and fig. 20-8)
(6) Excavators (Fig. 20-9)
(7) Backhoe loaders (Fig. 20-10)
(8) Graders (Fig. 20-11)
(9) Skid steer loaders (Fig. 20-12)
Appendix A
INDEX