CE2251 Soil QB

1

SUBJECT CODE: CE2251

SUBJECTNAME : Soil Mechanics

UNIT-I

SOIL INTRODUCTION

PART-A

OBJECTIVES

1. The maximum shear stress occurs on the filament which makes an angle with the horizontal plane equal to

A. 30° B.

45°

C. 60° D.

90°

2. For determining the moisture content of a soil sample, the following data is available Weight of container =

260 g, Weight of soil sample and = 320 g container, Weight of soil sample (dried) and = 310 g container.

The moisture content of the soil sample, is

A. 15% B.

18%

C. 20% D.

25%

3. Buoyant unit weight equals the saturated density

A. multiplied by unit weight of water

B. divided by unit weight of water

C. plus unit weight of water

D. minus unit weight of water.

4. Pick up the correct statement from the following:

A. An unconfined compression test is a special case of triaxial compression test

B. An unconfined compression test is a special case of direct shear test

C. The confining pressure is maximum during an unconfined compression test

D.

The cylindrical specimen of a soil is subjected to major principal stress till it fails due to shearing

along the plane of the failure.

5. A partially saturated soil is classified as

A. one phase soil

B. two phase soil

C. three phase soil

D. four phase soil.

6. The maximum shear stress occurs on the filament which makes an angle with the horizontal plane equal to

A. 30° B.

45°

C. 60° D.

90°

2

7. For determining the moisture content of a soil sample, the following data is available Weight of container =

260 g, Weight of soil sample and = 320 g container, Weight of soil sample (dried) and = 310 g container.

The moisture content of the soil sample, is

A. 15% B.

18%

C. 20% D.

25%

8. Buoyant unit weight equals the saturated density

A. multiplied by unit weight of water

B. divided by unit weight of water

C. plus unit weight of water

D. minus unit weight of water.


A. An unconfined compression test is a special case of triaxial compression test

B. An unconfined compression test is a special case of direct shear test

C. The confining pressure is maximum during an unconfined compression test

D.

The cylindrical specimen of a soil is subjected to major principal stress till it fails due to shearing

along the plane of the failure.

10. A partially saturated soil is classified as

one phase soil

B. two phase soil

C. three phase soil

D.

four phase soil.

11. Pick up the in-correct statement from the following: The soils which contain montmorillonite

minerals

A. swell more when wet

B. shrink more when dry

C. possess high plasticity

D. possess high coefficient of internal coefficient

E. None of these.

12. For determing the specific gravity of soil solids, using a pycnometer of 500 cc., the following data is

available : Weight of dry empty pycnometer = 125 g Weight of dried soil and pycnometer = 500 g Weight

of dried soil and distilled = 850 g water filled in pycnometer up to top The specific gravity of soil soilds, is

3

A. 2.0 B.

2.25

C. 2.50 D.

2.75


A. Kaolinite is most stable clay

B. Kaolinite shows a very little sign of swelling on wetting

C.

Kaolinite when wet, becomes moderately plastic because negative electro magnetic charges on

platelets attrack water

D. Kaolinite is also called China clay

E. All the above.

14. A pile is being driven with a drop hammer weighing 1800 kg and having a free fall of 1.00 m. If the

penetration with last blow is 5 mm, the load carrying capacity of the pile, -according to the Engineering

News formula, is

A. 100 tonnes

B. 50 tonnes

C. 20 tonnes

D. 10 tonnes.

15. If the specific gravity and voids in soil sample are G and e respectively, the hydraulic gradient i, is

A.

B.

C.

D.

16. Pick up the correct statement from the following :

A.

To an agriculturist, soil is the substance existing on the earth's surface, which grows and develops

plants

B.

To a geologist, soil is the material in a relatively thin surface zone within which roots occur, and

rest of the crust is termed as rock irrespective of hardness

C.

To an engineer, soil is the unaggregated and uncemented deposits of minerals and organic

particles covering the earth's crust

D. All the above.

17. The ratio of settlement at any time 't' to the final settlement, is known as

4

A. co-efficient of consolidation

B. degree of consolidation

C. consolidation index

D. consolidation of undisturbed soil.

18. The Westergaard analysis is used for

A. sandy soils

B. cohesive soils

C. stratified soils

D. clayey soils.

19. If L and B are the length and breadth of a footing, e the eccentricity along the length and P and Q are the

axial force and bearing capacity of the soil, then, to avoid tension,

A.

B.

C.

D.

20. 260 g of wet soil was taken in a pycnometer jar of weight 400 g in order to find the moisture content in the

soil, with specific gravity of soil particles 2.75. The weight of soil and remaining water filled in pycnometer

without air bubbles was 1415 g and the weight of pycnometer filled with water alone was 1275 g. The

moisture content in the soil is

A. 24.2%

B. 18.2%

C. 53.8%

D. none of these.

PART-B

21.Define soil?

Uncemented or weakly cemented accumulation of mineral and organic particles and sediments found above the

bedrock,unconsolidated material consisting of discrete solid particles with fluid or gas in the voids.

22. Define Soil Mechanics

5

According to (ASTM) Soil Mechanics Isdefine as the application of the laws and principles of mechanics and

hydraulics to engineering problems dealing with soil as an engineering material.

23. List the Main Types of Soils

The types of soil are, Granular: gravel, sand, (silt) ,Cohesive: (silt), clay ,Organic: marsh soil, peat, coal, tar

sand ,Man-Made: mine tailings, landfill waste, ash, and aggregates.

24.Define soil Index

emax = maximum void ratio corresponding to the loosest state, emin = minimum void ratio corresponding to

the densest state, and e = void ratio of the sample.

25. Give an empirical correlation between PSD and permeability.

An empirical correlation between PSD and permeability has been developed k = c (D10)2 cm/s Where 100 < c

< 150 Developed by Hazen for uniform, loose, clean sands and gravels.

26. Define degree of saturation.

The degree of saturation is defined as the ratio of volume of water to the volume of voids

27. Define Void Ratio

The void ratio of a soil is defined as the ratio of volume of voids to the volume of solids.

28. Define specific gravity.

It is defined as the ratio of the mass of a given volumes of solid gains to the mass of equal volume of water at

the same temperature

29. Define Density

The density of a substance is the mass per unit volume of that substance. For water this is denoted by w, and its

value is about 1000 kg/m3. Small deviations from this value may occur due to temperature differences or

variations in salt content. In soil mechanics these are often of minor importance, and it is often considered

accurate enough to assume that w = 1000 kg/m3.

30. Define water content.

By definition the water content w is the ratio of the weight (or mass) of the water and the solids,

w = Ww/Wp.

31. What are the factors that affect hydraulic conductivity?

The hydraulic conductivity is influenced by a number of factors including:

- Effective porosity

- Grain size and grain size distribution

- Shape and orientation of particles

- Degree of saturation

- Clay mineralogy

32. What are assumptions made to derive the equation governing two dimensional steady state seepage?

Several assumptions are required to derive the equation governing two dimensional steady state

seepage.

• The soil is completely saturated

• There is no change in void ratio of the porous medium

• The hydraulic conductivity is isotropic

• Darcy’s law is valid

• The water is incompressible

33. What are the steps in the construction of a flownet?

Steps in Drawing a Flow Net

1) Define and clearly mark a datum.

2) Identify the boundary conditions (EP, FL, LCP).

3) Draw intermediate equipotentials and flow lines.

6

- draw coarse mesh with a few EPs and FLs

4) Verify the coarse mesh is correct.

34. Define Permeability.

The ease with which water can flow through a soil mass is termed as permeability

35. What is laminar flow.

Flow of fluids is described as laminar if a fluid particles flow follows a definite path and does not cross

the path of other particles.

36. Define quick sand

Sand is said to be quick sand condition when the flow is upward under a hydraulic gradient, which

reduces the effective stress to zero.

37. What is Frost heave

Water migrates upward from the water table to the capillary fringe. When the atmospheric temperature falls to

the freezing point & the ice is formed. This results in an increase in the volume of the soil. This is known as

frost heave.

38. Give the Allen Hazens Formula

K=cD102

K- Co-efficient of permeability

D10- Effective size(cm)

c-constant with a value between 100& 500. Estimate the value of k of a soil with an effective diameter of 0.2

mm.

K=cD102

C= 125, K= 125 x 0.022

39. What are the approximate methods of determination of vertical stress under loaded areas?

· Equivalent point load method

· Two to one load distribution method

· Sixty degree distribution

40. What are the reasons for compression of the soil?

· Compression of solid particles & water in the voids.

· Compression & expulsion of air in the voids.

· Expulsion of water in the voids.

PART-C

41. What are assumptions made to derive theequation governing two dimensional steadystate seepage?

42. What are the steps in the construction of aflownet?

43. Give the formulae to determine the verticalstress, radial stress Tangential stress,&shearstressuner a point loadWhat is

Immediate settlement

44. List the assumptions made in the Laplace’sequation

45. What are the rules to be followed while construction of flow net?

UNIT-2

SOIL WATER AND WATER FLOW

PART-A

OBJECTIVE 46. The earth pressure of a soil at rest, is proportional to (where υ is the angle of internal friction of the soil)

A. tan (45° - υ)

B. tan (45° + υ)

7

C. tan

2 (45° - υ)

D. tan

2 (45° + υ)

E. none of these

47. A fundamental equation of void ratio(e), specific gravity (G), water content (ω) and degree of saturation

(Sr) is

A.

e =

B.

ω =

C.

G =

D.

Sr =

48. The critical exist gradient of seepage water in soils, is

A. directly proportional to the voids ratio

B. inversely proportional to the specific gravity

C. directly proportional to the specific gravity

D. inversely proportional to the voids ratio

E. none of these.

49. Water content of a soil sample is the difference of the weight of the given sample at the given temperature

and the weight determined after drying it for 24 hours at temperature ranging from

A. 80° to 90°C

B. 90° to 95°C

C. 95° to 100°C

D. 103° to 105°C

E. 105° to 110°C

50. The ratio of the volume of voids to the total volume of the given soil mass, is known

A. porosity

B. specific gravity

C. void ratio

D. water content.

8

51. The compression index of a soil

A. decreases with an increase in the liquid limit

B. increases with an increase in the liquid limit

C. decreases with an increase in the plastic limit

D. is not related with plastic limit.


A.

The void space between the soil grains, is filled partly with air and partly

with water

B. In perfectly saturated soil, the voids are completely filled with water

C. In dry soil, the voids are completely filled with air

D. all the above.

53. For a homogeneous earth dam 50 m high having 2 m free broad, a flow net was

constructed and the results were : Number of potential drops = 2.4 Number of flow

channels = 0.4. If coefficiency of permeability of the dam mateiral is 3 x 10-

3 cm

3/sec, the discharge per metre length of dam, is

A. 12 x 10

-5 m

3/sec

B. 24 x 10

-3 m

3/sec

C. 6 x 10

-5 m

3/sec

D. 24 x 10

-5 m

3/sec

54. W is the weight of soil having a moisture content ω. If V is the volume of proctor's

mould, the dry density of the soil is

A.

B.

C.

D.

55. For shear strength, triaxial shear test is suitable because

A. it can be performed under all three drainage conditions

B. precise measurement of the pore pressure and volume change during the

9

test is possible

C. stress distribution on the failure plane, is uniform

D.

state of stress within the specimen during any stage of the test as well as

at failure, is completely determined

E. all the abov

56. The degree of saturation of the soil sample stated in Q. No, 216, is

A. 60% B.

62%

C. 64% D.

66%

57. Number of piles required to support a column, is

A. 1 B.

2

C. 3 D.

4

58. The soil moisture driven off by heat, is called

A. free water

B. hydroscopic water

C. gravity water

D. none of these.

59. If the specific gravity of a soil particle of 0.05 cm diameter is 2.67, its terminal velocity while settling in

distilled water of viscosity, 0.01 poise, is

A. 0.2200 cm/sec

B. 0.2225 cm/sec

C. 0.2250 cm/sec

D. 0.2275 cm/sec

E. 0.2300 cm/sec

60. The direct shear test suffers from the following disadvantage:

A. Drain condition cannot be controlled

B. Pore water pressure cannot be measured

C. Shear stress on the failure plane is not uniform.

D. The area under the shear and vertical loads does not remain constant throughout the test

E. All the above.

61. For a clay slope of height of 10 m, the stability number is 0.05, γ = 2.0 t/m3, C = 2.5 t/m

2, the critical height

10

of the slope of the soil, is

A. 4.0 m

B. 12.5 m

C. 25.0 m

D. 15.0 m

62. If σ0' and σ' represent initial and increased pressure ; e0 and e void ratios corresponding to initial and

increased pressure ; and C0 the compression index (dimensionless), then, the virgin compression curve as

expressed by Terzaghi empirical formula is

A. e = e0 + Cc log10 σ'/σ0'

B. e = e0 - Cc log10 σ'/σ0'

C. e0 = e - Cc log10 σ'/σ0'

D. e0 = e + Cc log10 σ'/σ0'

63. The equation τ = C + σ tan υ is given by

A. Rankine B.

Coulomb

C. Culaman D.

Mohr.

64. You are given a sample of soil containing coarse grains to determine its water content, you will use

A. pycnometer

B. oven-drying method

C. calcium carbide method

D. alcohol method.

65. Pick up the incorrect statement from the following:

A. Compaction has no effect on the structure of a soil

B. Permeability decreases with increase in the dry density of a compacted soil

C. A wet side compacted soil is more compressible than a dry side compacted soil

D. Dry side compaction soils swell more when given access to moisture

E. None of the these.

PART-B

66. Define effective stress.

Effective stress equals the total stress minus the pore water pressure, or the total force in the soil grains

divided by the gross cross-sectional area over which the force acts.

67. Define Critical Depth.

If there is no distinct change in the character of subsurface strata within the critical depth, elastic

11

solutions for layered foundations need not be considered. Critical depth is the depth below the foundation

within which soil compression contributes significantly to surface settlements. For fine-grained compressible

soils, the critical depth extends to that point where applied stress decreases to 10 percent of effective

overburden pressure. In coarse-grained material critical depth extends to that point where applied stress

decreases to 20 percent of effective overburden pressure.

68. What are the rules to be followed while construction of flow net? rules for flow net construction

1. When materials are isotropic with respect to permeability, the pattern of flow lines andequipotentials

intersect at right angles. Draw a pattern in which square figures are formed between flow lines and

equipotentials

2. Usually it is expedient to start with an integer number of equipotential drops, dividing total head by a whole

number, and drawing flow lines to conform to these equipotentials. In the general case, the outer flow path will

form rectangular rather then square figures. The shape of these rectangles (ratio b/l) must be constant.

3. The upper boundary of a flow net that is at atmospheric pressure is a "free water surface". Integer

equipotentials intersect the free water surface at points spaced at equal vertical intervals.

69. Write a note on piping.

Piping and Subsurface Erosion. Most piping failures are caused by subsurface erosion in or beneath dams.

These failures can occur several months or even years after a dam is placed into operation.

70. Define Porosity

Soils usually consist of particles, water and air. In order to describe a soil various parameters are used to

describe the distribution of these three components, and their relative contribution to the volume of a soil. These

are also useful to determine other parameters, such as the weight of the soil. They are defined in this chapter.

An important basic parameter is the porosity n, defined as the ratio of the volume of the pore space and the total

volume of the soil, n = Vp/Vt.

71. What is Degree of saturation?

The pores of a soil may contain water and air. To describe the ratio of these two the degree of saturation S is

introduced as S = Vw/VpHere Vw is the volume of the water, and Vp is the total volume of the pore space. The

volume of air (or any other gas) per unit pore space then is 1 - S. If S = 1 the soil is completely saturated, if S =

0 the soil is perfectly dry.

72. Define water content

The water content is another useful parameter, especially for clays. It has been used in the previous chapter. By

definition the water content w is the ratio of the weight (or mass) of the water and the solids, w = Ww/Wp.

73. Define stress path.

A convenient way to represent test results, and their correspondence with the stresses in the structure.

74. What is the significance of soil mechanics?

Soil mechanics has become a distinct and separate branch of engineering mechanics because soils have a

number of special properties, which distinguish the material from other materials. Its development has also been

stimulated, of course, by the wide range of applications of soil engineering in civil engineering, as all structures

require a sound foundation and should transfer its loads to the soil. The most important special properties of

soils will be described briefly in this chapter. In further chapters they will be treated in greater detail,

concentrating on quantitative methods of analysis.

75. Write a short note on shear.

In compression soils become gradually sti_er. In shear, however, soils become gradually softer, and if the shear

stresses reach a certain level, with respect to the normal stresses, it is even possible that failure of the soil mass

occurs. This means that the slope of a sand heap, for instance in a depot or in a dam, can not be larger than

about 30 or

76. what are the reasons for the particles

12

would slide over each other at greater slopes. As a consequence of this phenomenon many countries in deltas of

large rivers are very flat. It has also caused the failure of dams and embankments all over the world, sometimes

with very serious consequences for the local population. Especially dangerous is that in very fine materials,

such as clay, a steep slope is often possible for some time, due to capillary pressures in the water, but after some

time these capillary pressures may vanish.

77. What is creep?

The deformations of a soil often depend upon time, even under a constant load. This is called creep.

78. Define plastic limit.

The transition from the plastic state to the solid state is called the plastic limit, and denoted as wP . It is defined

as the water content at which the clay can just be rolled to threads of 3 mm diameter. Very wet clay can be

rolled into very thin threads, but dry clay will break when rolling thick threads.

79. Define liquid limit.

The transition from the liquid state to the plastic state is denoted as the liquid limit, wL. It represents the lowest

water content at which the soil behavior is still mainly liquid.

80. What are methods available for determination ofk for a soil sample?

· Constant Head permeability test

· Falling Head Permeability Test

· Horizontal Capillary Test.

81. What is primary consolidation settlement?

The settlement which results of volumechange in the saturated cohesive soils because ofexpulsion of the water

that occupies the voids space.Give the formulae to determine the vertical stress,radial stress Tangential stress,&

shear stress unerauniformly distributed load load


The ease with which water can flow through asoil mass is termed as permeability


Flow of fluids is described as laminar if a fluidparticles flow follows a definite path and does not crossthe path

of other particles.


Sand is said to be quick sand condition whenthe flow is upward under a hydraulic gradient, whichreduces the

effective stress to zero.


Water migrates upward from the water table tothe capillary fringe. When the atmospheric temperaturefalls to

the freezing point & the ice is formed.This resultsin an increase in the volume of the soil. This is known asfrost

heave.

PART-C 86. What are the rules to be followed whileconstruction of flow net?

87. Define Seepage velocity.The actual velocity of water flowingthrough the voids is termed as seepage

velocity.

88. What are the factors that affect thepermeability of a soil mass?


90. Estimate the value of k of a soil with aneffective diameter of 0.2 mm.

UNIT-3

STRESS DISTRIBUTION,COMPRESSBILITY AND SETTLEMENT

PART-A

OBJECTIVE 91. The compressibility of clays, is caused due to:

A. expulsion of double layer water from in between the grains

13

B. sliping of particles to new positions of greater density

C. bending of particles as elastic sheets

D. all the above.

92. A phreatic line is defined as the line within a dam section below which there are

A. positive equipotential lines

B. positive hydrostatic pressure

C. negative hydrostatic pressure

D. negative equipotential lines

E. none of these.

93. The ratio of the difference between the void ratio of the soil in its loosest state and its natural void ratio (e)

to the difference between the void ratios in the loosest and fully dense state, is generally termed as

A. degree of density

B. relativity

C. density index

D. all the above.


A.

The property of a soil that enables it to become stiff in a relatively short time on standing is

called thixotropy

B.

The ratio of shear strength in natural state to the remoulded shear strength under

undrainedconditions, is called degree of sensitivity.

C.

The difference between the undisturbed shear strength and remoulded shear strength is

known remoulding loss

D. The tendency of dense sand to expand on application of shearing load, is known as dilatancy

E. All the above.

95. According to the Indian Standards the specific gravity is the ratio of the unit weight of soil solids to that of

water at a temperature of

A. 17°C B.

23°C

C. 27°C D.

30°


A. Illite bond is weaker than Kaolinite bond

B. Illite bond is stronger than montmorillonite bond

14

C. Illites do not swell when wet

D. Illites are composed of two silica tetrahedralsheets with a central octahedral sheet

E. All the above.

97. Determination of water content of a soil sample suspected to contain gypsum is made by drying the sample

for longer period at a temperature not more than

A. 60°C B.

80°C

C. 100°C D.

110°C

98. Water formed transported soil is

A. alluvial B.

marine

C. lacustrine D.

loess.

99. A decrease in water content results in a reduction of the volume of a soil in

A. liquid state

B. plastic state

C. semi solid state

D. all of these.


A. If the ratio of depth to width is less than 2, it is shallow foundation

B. If the ratio of depth to width is more than 2, it is deep foundation

C. If the ratio of the length to width is between 1 and 2, it is spread foundation

D. If the length is large as compared to width, it is a strip foundation

E. All the above.

101. The vane shear test is used for the in-situ determination of the undrained strength of the intact fully

saturated

A. sands

B. clays

C. gravels

D. highly organic soils.

102. Fundamental relationship between dry density (γd), bulk density (γ) and water content (ω), is :

A.

γ =

15

B.

γd =

C.

ω =

D.

ω =

103. The specific gravity of quartz, is

A. 2.65 B.

2.72

C. 2.85 D.

2.90

104. If the cohesive force, (c), is 1.5 t/m2, the density (γ) of the soil is 2.0 t/m

3, factor of safety (F) is 1.5 and

stability factor (Sn) is 0.05, the safe height of the Â§lope, is

A. 5 metres

B. 8 metres

C. 10 metres

D. 12 metres


A. The phenomenon of quicksand generally occurs in the cohesionless soil

B. At critical hydraulic gradient, the saturated sand becomes quick

C. The critical gradient depends on the void ratio and the specific gravity

D. The quick sand occurs more in fine sand and silt than coarse material (e) All the above.

106. If W1, W2, W3 and W4 are the sequential weights obtained during observations in pycnometer method for

determining water content, the formula to be used, is

A.

W =

B.

W =

C.

W =

D.

W =

16

107. Si particles

A. show dilatancy

B. swell when moist

C. possess high strength when dry

D. disintegrate easily.

108. Flow net is used for the determination of

A. quantity of seepage

B. hydrostatic pressure

C. seepage pressure

D. exit gradient

E. all the above.

109. If the back fill is having a uniform surcharge of intensity q per unit area, the lateral pressure will be

A. q times the lateral pressure within the surface

B. 1/q times the lateral pressure within the surface

C. equal to a fill of height Z equal to q/r, where r is the density of the backfill

D. none of these.


A.

Isotropic consolidation of clay can be obtained in the triaxial apparatus under equal all-round

pressure.

B.

If the present effective stress is the maximum to which the clay has ever been subjected, it is

called normally consolidated clay

C.

If the present effective stress in the past was more than present effective stress, it is called over-

consolidated clay

D. All the above.

PART-B 201. What is Darcy’s law?

For laminar flow in a homogeneous soil thevelocity of flow (v) is given byV= KiK= co-efficient of

permeabilityI-hydraulic gradient.

202. Define seepage.

Seepage is the flow of water undergravitational forces in a permeable medium. The flowis generally Laminar.

203. List the assumptions made in the Laplace’sequation

The following assumptions are made in thederivation of the Laplace equation.

•The flow is laminar.

17

•Water & soil are incompressible.

•Soil is isotropic & homogeneous.

•The soil is fully saturated.

•The flow is steady ie. flow condition do notchange with time.

•Darcy’s law is valid

.204.What are the approximate methods ofdetermination of vertical stress under loadedareas?

•Equivalent point load method

•Two to one load distribution method

•Sixty degree distribution

205. What are the reasons for compression of thesoil?

•Compression of solid particles & water in thevoids.

•Compression & expulsion of air in the voids.

•Expulsion of water in the voids.

206. What are the stages of consolidation?

The stages of consolidation are

•Initial consolidation

•Primary consolidation

•Secondary consolidation

207. What is a principal plane?

At every point in a stressed body, thereare three planes on which the sher stress arezero. These planes are known as principalplanes.

208. What are the limitations of coulomb’s theory?

The limitations of columb theory are

•It neglects the effect of the intermediate principalstress.

•It approximates the curved failure envelope by astraight line which may not give correct results.

209. Give the Coulomb’s shear strength equation.

The Coulomb’s shear strength equation isgivenby,S= c+σ

tan C= cohesion= Angle of internal friction

210. What is Unconsolidated- Undrained condition?

In this type of test no drainage is permittedduring the consolidation stage. The drainage is alsopermitted in the

shear stage.

211. What is consolidated- undrained condition?

In a consolidated- undrained test, the specimenis allowed to consolidate in the first stage. The drainageis

permitted until the consolidation is complete.

212. What is the main cause of slope failue?

Slope failures occur when the rupturing forceexceeds resisting force.

What are the factors affecting permeabilitytests?

The following five physicalcharacteristics influence the performance andapplicability of permeabilitytests:(1)

position of the water level,(2) type of material - rock or soil,(3) depth of the test zone,(4) permeability of the

test zone, and(5) heterogeneity and anisotropy of the test zone.


Effective stress equals the total stress minus thepore water pressure, or the total force in the soil grainsdivided

by the gross cross-sectional area over which theforceacts.Define Critical Depth.If there is no distinct change in

the character ofsubsurface strata within the critical depth, elasticsolutions for layered foundations need not

beconsidered. Critical depth is the depth below thefoundation within which soil compression

contributessignificantly to surface settlements. For fine-grainedcompressible soils, the critical depth extends to

thatpoint where applied stress decreases to 10 percent ofeffective overburden pressure. In coarse-grained

214. Give an empirical correlation between PSDand permeability.

An empirical correlation between PSD andpermeability has been developedk = c (D10)2 cm/sWhere 100 < c <

150Developed by Hazen for uniform, loose, clean sandsand gravels.


The degree of saturation is defined as theratio of volume of water to the volume of voids

18


The void ratio of a soil is defined as the ratio ofvolume of voids to the volume of solids.

217. Define specific gravity

.It is defined as the ratio of the mass of a givenvolumes of solid gains to the mass of equal volume ofwater at


218. Define Density

The density of a substance is the mass per unitvolume of that substance. For water this is denoted byw, and its

value is about 1000 kg/m3. Small deviationsfrom this value may occur due to temperaturedifferences or

variations in salt content. In soilmechanics these are often of minor importance, and it isoften considered

accurate enough to assume that w =1000 kg/m3.


.By definition the water content w is the ratio ofthe weight (or mass) of the water and the solids,w = Ww /Wp.

220. What are the factors that affect hydraulicconductivity?

The hydraulic conductivity is influenced by anumber of factors including:- Effective porosity- Grain size and

grain size distribution- Shape and orientation of particles- Degree of saturation

-Clay mineralogy

PART-C 221. Give the formulae to determine the verticalstress, radial stress Tangential stress,&shearstressuner a point loadWhat is


222. Give the formulae to determine the verticalstress, horizontal stress under a circularload

223. Give the Coulomb’s shear strength equation.

224. Write a note on piping.

225. What are methods available for determination ofk for a soil sample?

UNIT-4

SHEAR STRENGTH

PART-A

OBJECTIVE 226. The fundamental equation of specific gravity (G), dry density (γd), unit weight of water (γω) and void ratio

(e), is

A.

e =

B.

G =

C.

γd =

D.

γω =

227. Negative skin friction on piles

A. is caused due to relative settlement of the soil

B. is caused in soft clays

C. decreases the pile capacity

D. all of the above.

19

228. Fine sand possesses

A. good plasticity

B. limited plasticity

C. reasonable plasticity

D. clay.

229. The ultimate bearing capacity of a soil, is

A. total load on the bearing area

B. safe load on the bearing area

C. load at which soil fails

D. load at which soil consolidates.

230. Transporting and redepositing soils, is done by

A. water

B. glacier

C. gravity

D. wind

E. all the above.

231. A moist soil sample of volume 60 cc. weighs 108 g and its dried weight is 86.4 g. If its absolute density is

2.52, the degree of saturation is

A. 54% B.

64%

C. 74% D.

84%


A.

O.M.C. refers to the moisture corresponding to the maximum point on the moisture content dry

density curve

B.

The line which shows moisture content dry density relation for soil containing a constant

percentage of air voids, is known as air void line

C. The weight of hammer used for compaction test is 25 kg

D. The free fall of hammer for compaction is 30.5 cm

E. All the above.

233. The passive earth pressure of a soil, is proportional to (where υ is the angle of internal friction of the soil.)

A. tan (45° - υ)

B. tan (45° + υ)

20

C. tan

2 (45° - υ

D. tan

2 (45° + υ)

234. If a soil undergoes a change in shape and volume by application of external loads over it, but recovers its

shape and volume immediately after removal of the load, the property of the soil is said to be

A. Resilience of soils

B. Elasticity of soils

C. Compressibility of soils

D. None of these.

235. If the unit weight of sand particles is 2.696 g/cc. and porosity in loose state is 44%, the critical hydraulic

gradient for quick sand condition, is

A. 0.91 B.

0.92

C. 0.93 D.

0.94

E. 0.95

236. The void ratio of a soil sample decreases from 1.50 to 1.25 when the pressure is increased from 25

tonnes/m2 to 50 tonnes/m

2, the coefficient of compressibility is

A. 0.01 B.

0.02

C. 0.05 D.

0.001


A. The smaller the size of the pores, the higher the water can rise above the water table.

B. Below the water table, the pore water may be static.

C. The hydrostatic pressure depends on the depth below the water level.

D.

The attractive forces between the particles, caused due to negative pressure of water held above

the water table is called soil suction.

E. None of these.

238. The maximum water content at which a reduction in water content does not cause a decrease in volume of a

soil mass, is known

A. liquid limit

B. plastic limit

C. shrinkage limit

D. permeability limit.

21

239. A sample of saturated soil has 30% water content and the specific gravity of soil grains is 2.6. The dry

density of the soil mass in g/cm3, is

A. 1.47

B. 1.82

C. 1.91

D. none of these.

240 . The specific gravity of sands, is approximately

A. 1.6 B.

2.0

C. 2.2 D.

2.4

E. 2.6

241 . If the coefficients of volume change and compressibility of a soil sample are

respectively 6.75 x 10-2

and 3 x 10-2

, the void ratio of the soil sample, is

A. 1.10 B.

1.15

C. 1.20 D.

1.25

E. 1.30

242 . The minimum centre to centre distance of friction piles of 1 m diameter, is

A. 2 m

B. 2 m to 3 m

C. 3 m to 4 m

D. 5 m

243 . Over-consolidation of soils is caused due to

A. erosion of over burden

B. melting of ice sheets after glaciation

C. permanent rise of water table

D. all the above.

244 .Darcy's law is applicable to seepage if a soil is

A. homogeneous

B. isotropic

C. incompressible

D. all the above.

245 .S An infinite slope is inclined at angle i and has its angle of internal friction υ, the

22

stability number Sa, is

A.

B.

C. (tan i - tan υ) cos

2 i

D. (tan i - tan υ) sin

2 i

PART-B 246. What is Unconsolidated- Undrained condition?


shear stage.

247. What is consolidated- undrained condition?

In a consolidated- undrained test, the specimenis allowed to consolidate in the first stage. The drainageis

permitted until the consolidation is complete.

248. What is the main cause of slope failue?

Slope failures occur when the rupturing forceexceeds resisting force.

The following five physicalcharacteristics influence the performance andapplicability of permeabilitytests:(1)

position of the water level,(2) type of material - rock or soil,(3) depth of the test zone,(4) permeability of the

test zone, and(5) heterogeneity and anisotropy of the test zone.


Effective stress equals the total stress minus thepore water pressure, or the total force in the soil grainsdivided

by the gross cross-sectional area over which theforceacts.Define Critical Depth.If there is no distinct change in

the character ofsubsurface strata within the critical depth, elasticsolutions for layered foundations need not

beconsidered. Critical depth is the depth below thefoundation within which soil compression

contributessignificantly to surface settlements. For fine-grainedcompressible soils, the critical depth extends to

thatpoint where applied stress decreases to 10 percent ofeffective overburden pressure. In coarse-grained








253. Define Density






.By definition the water content w is the ratio ofthe weight (or mass) of the water and the solids,

w = Ww/Wp.




-Clay mineralogy

256.Define soil?

23

Uncemented or weakly cemented accumulation of mineral and organic particles and sediments found above the

bedrock,unconsolidated material consisting of discrete solid particles with fluid or gas in the voids.

257. Define Soil Mechanics

According to (ASTM) Soil Mechanics Isdefine as the application of the laws and principles of mechanics and

hydraulics to engineering problems dealing with soil as an engineering material.

258. List the Main Types of Soils

The types of soil are, Granular: gravel, sand, (silt) ,Cohesive: (silt), clay ,Organic: marsh soil, peat, coal, tar

sand ,Man-Made: mine tailings, landfill waste, ash, and aggregates.

259.Define soil Index

emax = maximum void ratio corresponding to the loosest state, emin = minimum void ratio corresponding to

the densest state, and e = void ratio of the sample.

260. Give an empirical correlation between PSD and permeability.

An empirical correlation between PSD and permeability has been developed k = c (D10)2 cm/s Where 100 < c

< 150 Developed by Hazen for uniform, loose, clean sands and gravels.


The degree of saturation is defined as the ratio of volume of water to the volume of voids


The void ratio of a soil is defined as the ratio of volume of voids to the volume of solids.

263. Define specific gravity.

It is defined as the ratio of the mass of a given volumes of solid gains to the mass of equal volume of water at


264. Define Density

The density of a substance is the mass per unit volume of that substance. For water this is denoted by w, and its

value is about 1000 kg/m3. Small deviations from this value may occur due to temperature differences or

variations in salt content. In soil mechanics these are often of minor importance, and it is often considered

accurate enough to assume that w = 1000 kg/m3.

265. Define water content.

By definition the water content w is the ratio of the weight (or mass) of the water and the solids,

w = Ww/Wp.

PART-C


267. Define and clearly mark a datum.2) Identify the boundary conditions (EP, FL, LCP).3) Draw

intermediate equipotentials and flow lines.- draw coarse mesh with a few EPs and FLs4) Verify the

coarse mesh is correct.



269. What are the approximate methods of determination of vertical stress under loaded areas?

270. What are the factors affecting permeability tests and explain detail.

UNIT-5

SLOPE STABILITY

PART-A

OBJECTIVE

271. Depending upon the properties of a material, the failure envelope may

A. be either straight or curved

24

B. pass through the origin of stress

C. intersect the shear stress axis

D. all the above.

272. A stratum of clay 2 m thick will get consolidated 80% in 10 years. For the 80% consolidation of 8 m thick

stratum of the same clay, the time required is

A. 100 years

B. 120 years

C. 140 years

D. 160 years

E. 180 years.

273. The maximum net pressure intensity causing shear failure of soil, is known

A. safe bearing capacity

B. net safe bearing capacity

C. net ultimate bearing capacity

D. ultimate bearing capacity.

274. The factor which affects the compaction, is

A. moisture content

B. compacting content

C. method of compaction

D. type of soil

E. All the above.

275. The compression resulting from a long term static load and consequent escape of pore water, is known as

A. compaction

B. consolidation

C. swelling

D. none of these.

276. Soil classification of composite soils, exclusively based on the particle size distribution, is known

A. particle classification

B. textural classification

C. High Way Research Board classification

25

D. unified soil classification.

277. The coefficient of curvature for a well graded soil, must be between

A. 0.5 to 1.0

B. 1.0 to 3.0

C. 3.0 to 4.0

D. 4.0 to 5.0

278. Fundamental relationship between dry density (γd), specific gravity (G), water content (ω) and percentage

of air voids (na) is :

A.

γd =

B.

γd =

C.

γd =

D.

γd =

279. A moist soil sample weighing 108 g has a volume of 60 cc. If water content is 25% and value of G = 2.52,

the void ratio is

A. 0.55 B.

0.65

C. 0.75 D.

0.80

280. The shear resistance of a soil is con-tituted basically of the following component.

A.

The frictional resistance to translocation between the individual soil particles at their contact

point

B. To the structural relation to displacement of the soil because of the interlocking of the particles

C. Cohesion and adhesion between the surfaces of the soil particles

D. All the above.

281. The void ratio of a soil sample decreases from 1.50 to 1.25 when the pressure is increased from 25

tonnes/m2 to 50 tonnes/m

2, the coefficient of compressibility is

A. 0.01 B.

0.02

C. 0.05 D.

0.001


26

A. The smaller the size of the pores, the higher the water can rise above the water table.

B. Below the water table, the pore water may be static.

C. The hydrostatic pressure depends on the depth below the water level.

D.

The attractive forces between the particles, caused due to negative pressure of water held above

the water table is called soil suction.

E. None of these.

283. The maximum water content at which a reduction in water content does not cause a decrease in volume of a

soil mass, is known

A. liquid limit

B. plastic limit

C. shrinkage limit

D. permeability limit.

284. A sample of saturated soil has 30% water content and the specific gravity of soil grains is 2.6. The dry

density of the soil mass in g/cm3, is

A. 1.47

B. 1.82

C. 1.91

D. none of these.

285. The specific gravity of sands, is approximately

A. 1.6 B.

2.0

C. 2.2 D.

2.4

E. 2.6

286. If the coefficients of volume change and compressibility of a soil sample are respectively 6.75 x 10-2

and 3

x 10-2

, the void ratio of the soil sample, is

A. 1.10 B.

1.15

C. 1.20 D.

1.25

E. 1.30

287. The minimum centre to centre distance of friction piles of 1 m diameter, is

A. 2 m

B. 2 m to 3 m

C. 3 m to 4 m

27

D. 5 m

288. Over-consolidation of soils is caused due to

A. erosion of over burden

B. melting of ice sheets after glaciation

C. permanent rise of water table

D. all the above.

289. Darcy's law is applicable to seepage if a soil is

A. homogeneous

B. isotropic

C. incompressible

D. all the above.

290. An infinite slope is inclined at angle i and has its angle of internal friction υ, the stability number Sa, is

A.

B.

C. (tan i - tan υ) cos

2 i

D. (tan i - tan υ) sin

2 i

PART-B

291. What is the significance of soil mechanics?

Soil mechanics has become a distinct andseparate branch of engineering mechanicsbecause soils have a number

of specialproperties, which distinguish the material fromother materials.

292. The following five physical characteristics influence the performance and applicability of

permeability tests:

(1) position of the water level,

(2) type of material - rock or soil,

(3) depth of the test zone,

(4) permeability of the test zone, and

(5) heterogeneity and anisotropy of the test zone.


Effective stress equals the total stress minus the pore water pressure, or the total force in the soil grains divided

by the gross cross-sectional area over which the force acts.

294. Define Critical Depth.

28

If there is no distinct change in the character of subsurface strata within the critical depth, elastic solutions for

layered foundations need not be considered. Critical depth is the depth below thefoundation within which soil

compression contributes significantly to surface settlements. For fine-grained compressible soils, the critical

depth extends to that point where applied stress decreases to 10 percent of effective overburden pressure. In

coarse-grained material critical depth extends to that point where applied stress decreases to 20 percent of

effective overburden pressure.

295. What are the rules to be followed while construction of flow net? rules for flow net construction

1. When materials are isotropic with respect to permeability, the pattern of flow lines andequipotentials

intersect at right angles. Draw a pattern in which square figures are formed between flow lines and

equipotentials

2. Usually it is expedient to start with an integer number of equipotential drops, dividing total head by a whole

number, and drawing flow lines to conform to these equipotentials. In the general case, the outer flow path will

form rectangular rather then square figures. The shape of these rectangles (ratio b/l) must be constant.



The settlement which is caused by the elasticdeformation of dry soil and of moist and saturated soilswithout any

change in moisture content.

297. What is primary consolidation settlement?

The settlement which results of volumechange in the saturated cohesive soils because ofexpulsion of the water

that occupies the voids space.Give the formulae to determine the vertical stress,radial stress Tangential stress,&

shear stress unerauniformly distributed load load


The ease with which water can flow through asoil mass is termed as permeability


Flow of fluids is described as laminar if a fluidparticles flow follows a definite path and does not crossthe path

of other particles.


Sand is said to be quick sand condition whenthe flow is upward under a hydraulic gradient, whichreduces the

effective stress to zero.


Water migrates upward from the water table tothe capillary fringe. When the atmospherictemperaturefalls to the

freezing point & the ice is formed.This resultsin an increase in the volume of the soil. This isknown asfrost

heave.

302. Give the Allen Hazens Formula

K=cD102K- Co-efficient of permeability

D10- Effective size(cm)c-constant with a value between 100& 500.

Estimate the value of k of a soil with aneffective diameter of 0.2 mm.

K=cD102

C= 125, K= 125 x 0.022








306. Define Density



29




.By definition the water content w is the ratio ofthe weight (or mass) of the water and the solids,

w = Ww/Wp




-Clay mineralogy


Several assumptions are required to derive theequation governing two dimensional steady stateseepage.

• The soil is completely saturated• There is no change in void ratio of the porous medium• The hydraulic

conductivity is isotropic• Darcy’s law is valid• The water is incompressible

310. What is Unconsolidated- Undrained condition?


shear stage.

PART-C


What is a principal plane?

312. What are assumptions made to derive the equation governing two dimensional steady state

seepage?

313. What are assumptions made to derive the equation governing two dimensional steady state seepage?

314. Write a short note on shear and explain their types

315. explain about methods of slices.

Documents

CE2251 Soil QB