soil mechanics jh academy question.pdf

Sub: Geotechnical Engineering

Topic : Three Phase System

MODULE-43C Origin of soils, soil classification, three-phase system, fundamental definitions, relationship and interrelationships, _________________________________________________________________________

1. The void ratio and specific gravity of a soil are 0.65 and 2.72 respectively. The degree of saturation (in percent) corresponding to water content of 20% is (A) 65.3 (B) 20.9 (C) 83.7 (D) 54.4 Ans: 0.65

0.544

0.2*2.72 1

2.72

2.

The avoid ratios at the densest, loosest and the natural states of a sand deposit are 0.2, 0.6 and 0.4, respectively. The relative density of the deposit is (A) 100% (B) 75% (C) 50% (D) 25%

Ans:

3.

The following data were obtained from a liquid limit lest conducted on a soil sample. Number of blows Water content (%)

17

22

25

28

34

68.3

63.1

61.9

60.6

60.5

The liquid limit of the soil is (A) 63.1 % (B) 62.8 % (C) 61.9 % (D) 60.6 %

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Ans: The water content at 25 blows is called Liquid limit. i.e. 61.9 4.

Data from a sieve analysis conducted on a given sample of soil showed that 67% of the particles passed through 75 micron IS sieve. The liquid limit and plastic limit of the finer fraction was found to be 45 and 33 percents respectively. The group symbol of the given soil as per IS: 1498-1970 is (A) SC

(B) MI

(C) CH

(D) MH

Ans: As more than 50 % of the total soil is finer than 75 fine grained soil CH H

CL

CI

ML

MI

12

20

35

the given soil is

MH 50

on the A-line, =18.25 The soil is below A-line. So the soil is MI 5.

The undrained cohesion of a remoulded clay soil is 10 kN/m2. If the sensitivity of the clay is 20, the corresponding remoulded compressive strength is (a) 5 kN/m2 (b) 10 kN/m2 2 (c) 20 kN/m (d) 200 kN/m2

Ans: Compressive strength = 2C =20 kN/m2 6.

The ratio of saturated unit weight to dry unit weight of dry unit weight is 1.25. If the specific gravity of solids (G s) is 2.65, the void ratio of the soil is (a) 0.625 (b) 0.663 (c) 0.944 (d) 1.325

Ans: e

e

2.65

1

e=0.663

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7.

A soil mass contains 40% gravel, 50% sand and 10% silt. This soil can be classified as (a) silty sandy gravel having coefficient of uniformity less than 60. (b) silty gravelly sand having coefficient of uniformity equal to 10. (c) gravelly silty sand having coefficient of uniformity greater than 60. (d) gravelly silty sand and its coefficient of uniformity cannot be determined. Ans: Soil of higher proportion comes in last 8.

3

A saturated soil mass has a total density 22kN/m and a water content of 10%. The bulk density and dry density of this soil are 3 3 (a) 12 kN/m and 20 kN/m respectively. 3 3 (b) 22 kN/m and 20 kN/m respectively. 3 3 (c) 19.8kN/m and19.8 N/m respectively. 3 3 (d) 23.2kN/m and19.8kN/m respectively.

Ans: The bulk density is equal to saturated density as the soil is in saturated 3 condition. i.e 22 kN/m .

9.

Sieve analysis on a dry soil sample of mass 1000 g showed that 980 g and 270 g of soil pass through 4.75 mm and 0.075 mm sieve, respectively. The liquid limit and plastic limits of the soil fraction passing through 425μ sieves are 40% and 18% respectively. The soil may be classified as (a) SC (b) MI (c) CI (d) SM

Ans: As 270 gm out of 1000gm pass through 75 sieve, the soil should be coarse grained. The remaining 730 gm of soil, the gravel is only 20 gm and 710 gm is sand. The sand fraction is more than gravel. So the soil should be sand. The percentage of fines is 27 %, which is more than 12 %. So we need to get information from A-line.

CL

CI

ML

MI

CH H

22

20

35

MH 50

on the A-line, =14.6 The soil is above A-line. So the soil is clayey. The classification is SC

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10. The water content of a saturated soil and the specific gravity of soil solids were found to be 30% and 2.70, respectively. Assuming the unit weight of water to be 10 kN/m3, the saturated unit weight (kN/m3) and the void ratio of the soil are (a) 19.4, 0.81 (b) 18.5, 0.30 (c) 19.4, 0.45 (d) 18.5, 0.45 Ans: 0.3*27

e

27

1

0.81

11. Group symbols assigned to silty sand and clayey sand are respectively (A) SS and CS (B) SM and CS (C) SM and SC (D) MS and CS Ans: Main soil symbol comes first 12. The liquid limit (LL), plastic limit (PL) and shrinkage limit (SL) of a cohesive soil satisfy the relation (A) LL>PLPL>SL (C) LLSL

volume

Ans:

Semi solid

solid

plastic

liquid

Water content

13. Deposit with flocculated structure is formed when (A) Clay particles settle on sea bed (B) Clay particles settle on fresh water lake bed (C) Sand particles settle on river bed (D) Sand particles settle on sea bed Ans: Deposit with flocculated structure is formed when sand particles settle on river bed 14. The laboratory test results of a soil sample are given below: Percentage finer than 4.75 mm = 60 Percentage finer than 0.075 mm = 30 Liquid Limit = 35% Plastic Limit = 27% The soil classification is (A) GM (B) SM (C) GC (D) ML-MI

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Ans: Coarse fraction =70 Fine fraction =30 As coarse fraction is more than fines, the soil is coarse grained. Gravel=40 and sand =30. So the soil is gravel. As fines are more than 12%, we need to check A-line.

CH H

CL

CI

ML

MI

20

35

MH 50

on the A-line, =10.95 The soil is above A-line. So the soil is silt. The classification is GM

15. In a compaction test, G, w, S and e represent the specific gravity, water content, degree of saturation and void ratio of the soil sample, respectively. If represents the unit weight of water and represents the dry unit weight of the soil. the equation for zero air voids line is (A)

(B)

(C)

(D)

Ans: wG

e

wG

1

16. A fine grained soil has liquid limit of 60 and plastic limit of 20. As per the plasticity chart. according to IS classification, the soil is represented by the letter symbols (A)CL (B)CI (C) CH (D) CL-ML

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Ans: CL

CI

ML

MI

CH H

40

20

35

MH 50

on the A-line, =29.2 The soil is above A-line. So the soil is clayey. The classification is CH

17. The results for sieve analysis carried out for three types of sand, P, Q and R, are given in the adjoining figure. If the fineness modulus values of the three sands are given as , it can be stated that

(A) (B) (C) (D)

√

Ans: Area under the curve represents fineness modulus. 18. As per the Indian Standard soil classification system, a sample of silty clay with liquid limit of 40% and plasticity index of 28% is classified as (A) CH (B) CI (C) CL (D) CL-ML Ans: A line equation, =14.6 The soil is above A-line and it is intermediate compressibility. So it is CI

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19. In its natural condition, a soil sample has a mass of 1.980 and a volume of 0.001 . After being completely dried in an oven, the mass of the sample is 1.800 . Specific gravity is 2.7. Unit weight of water is 10 . The degree of saturation of the soil is: (A) 0.65 (B) 0.70 (C) 0.54 (D) 0.61 Ans:

e 0.1*27

0.27

1

27

20. Match list-I (type of soil) with list-II (mode of transportation and deposition) and select the correct answer using the codes given below the lists: List – I A. Lacustrine soils B. Alluvial soils C. Aeolian soils D. Marine soils List-II 1. Transportation by wind 2. Transportation by running water 3. Deposited at the bottom of lakes 4. Deposited in sea water Codes: A B C D a.

1

2

3

4

b.

3

2

1

4

c.

3

2

4

1

d.

1

3

2

4

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Ans: (b) 21. The liquid limit and plastic limit of samples are 65% and 29% respectively. The percentage of soil fraction with grain size finger than 0.002 mm is 24. The activity ratio of the soil sample is (a) 0.05 (b) 1.00 (c) 1.50 (d) 2.00 Ans:

22. A soil sample as shrinkage limit of 10% and specific gravity soils as 2.7. The porosity of the soil at shrinkage limit is (a) 21.2%

(b) 27% (c) 73%

(d) 78.8%

Ans: 0.1*2.7

e=0.27 1 =0.212

23. In a wet soil mass, air occupies one-sixth of its volume and water occupies one-third of its volume. The void ratio of the soil is (a) 0.25

(b) 0.5 (c) 1.00

(d) 1.50

Ans: 1/6 1/3 0.5

24. Lacustrine soils are soils (a) Transported by rivers and streams (b) Transported by glaciers (c) Deposited in sea beds (d) Deposited in lake beds Ans: (d) 25. The standard plasticity chart to classify fine grained soils is shown in the given figure

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The area marked X represents a) b) c) d)

Silt of low plasticity Clay of high plasticity Organic soil of medium plasticity Clay of intermediate plasticity

Ans: (d) 26. A soil sample is having a specific gravity of 2.60 and a void ratio of 0.78. The water content in percentage required to fully saturate the soil at that void ratio would be (a) 10

(b) 30 (c) 50

(d) 70

Ans: 0.78

e=0.78 1 = 0.3

27. A dry soil has mass specific gravity of 1.35. If the specific gravity of solids is 2.7, Then the void ratio will be (a) 0.5

(b) 1.0 (c) 1.5

(d) 2.0

Ans: e 2.7

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1

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28. A clay sample has a void ratio of 0.50 in dry state and specific gravity of solids = 2.70. Its shrinkage limit will be (a) 12%

(b) 13.5% (c) 18.5%

(d) 22%

Ans: Shrinkage limit is nothing but water content at just saturated state.

0.5

e

2.7

1

0.5

29. A soil has liquid limit of 60% plastic limit of 35% and shrinkage limit of 20% and it has a natural moisture content of 50%. The liquidity index of soil is (a) 1.5 (b) 1.25 (c) 0.60

(d) 0.40

volume

Ans:

Water content

30. Consider the following statement in relation to the given sketch

1. 2. 3. 4.

Soil is partially saturated at degree of saturation = 60% Void ratio = 40% Water content = 30% Saturated unit weight=1.5 g/cc

Which of these statements is are correct? a)

1, 2 and 3

b) 1, 3 and 4

c)

2, 3 and 4

d) 1, 2 and 4

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Ans:

1.5 31. A soil has a liquid limit of 45% and lies above the A-line when plotted on a plasticity chart. The group symbol of the soil as per IS soil classification is (a) CH

(b) CI

(c) CL

(d) MI

Ans: (b) 32. The dry density of a soil is 1.5 g/cc. If the saturation water content were 50% then its saturated density and submerged density would, respectively, be (a) 1.5 g/cc and 1.0 g/cc (b) 2.0 g/cc and 1.0 g/cc (c) 2.25 g/cc and 1.25 g/cc (d) 2.50 g/cc and 1.50 g/cc Ans:

=1.5*(1+0.5)=2.25 g/cc

=2.25-1=1.25 33. A fill having a volume of 1,50,000 cum is to be constructed at a Void ratio of 0.8. The borrow pit soil has a void ratio of 1.4. The volume of soil required (in cubic meters) to be excavated from the borrow pit will be (a) 1,87,500

(b) 2,00,000

(c) 2,10,000

(d) 2,50,000

Ans: Mass of solids of fill = Volume of bowwow pit=

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34. The moisture content of a clayey soil is gradually decreased from a large value. What will be the correct sequence of the occurrence of the following limits? 1. Shrinkage limit 2.Plastic limit 3.Liquid limit Select the correct answer using the codes (a) 1,2,3 (b) 3,2,1

given below:

(c) 1,3,2 (d) 3,1,2

Ans: (b) 35. Given the Plasticity Index (PI) of a local soil =15 and PI of sand=Zero, for a described PI of 6, the percentage of sand in the mix should be (a) 70

(b) 60 (c) 40

(d) 30

Ans:

36. Consider the following statements: A Well-graded sand should have 1. 2. 3.

Uniformity coefficient greater than 6 Coefficient curvature between 1 and 3 Effective size greater than 1mm

Which of the statements are correct? (a) 1, 2 and 3 (b) 1 and 3

(c) 1 and 2 (d) 2 and 3

Ans: (c) 37. A Clayey soil has Liquid limit = , Plastic limit = and natural moisture content = . The consistency index of the soil is given by (a) (c) )

–

(b) (

–

)

(d) )

(

–

)

Ans: (a) 38. A soil has mass unit weight , water content ‘w’ (as ratio). The specific gravity of soil soilds = G, unit weight of water= ; ‘S’ is the degree of saturation of the soil is given by

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(a) S =

(b) S =

(c) S =

(d) S = Ans: e

wG

wG 1

G

39. The saturated and dry densities of a soil are respectively 2000kg/m³ and 1500 kg/m³. The water content (in percentage) of the soil in the saturated state would be (a) 25

(b) 33.33 (c) 50

(d) 66.66

Ans:

40. If a soil of sample weight 0.18kg having a volume of 10⁻⁴ m³ and dry unit weight of 1600 kg/m³ is mixed with 0.02 kg of water then the water content will be (a) 30%

(b) 25% (c) 20%

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(d) 15%

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Ans: Mass of solids=1600*10⁻⁴=0.16 kg Existing water=0.18-0.16=0.02 kg Additional water =0.02 kg Total water = 0.04kg Water content=0.04/0.16=0.25 41. Match List-I (terms) with List-II (formulae) and select the correct answer using the codes given below this list List-I

List-II

A. Void ratio

1.

B. Porosity

2.

C. Degree of saturation

3.

D. Water content

4. 5.

Codes A

B

C

D

5

1

(a)

4

3

(b)

5

4

(c)

4

(d)

5

3

1

1

5

2

1

3

2

Ans: (d) 42. If an unconfined compressive strength of 4 kg/cm² in the natural state of clay reduces by four times in the remoulded state, then its sensivity will be (a) 1 (b) 2

(c) 4

(d) 8

Ans: (c) 43. If the proportion of soil passing 75 micron sieve is 50% and the liquid limit and plastic limit are 40% and 20% respectively, then the group index of the soil is (a) 3.8

(b) 6.5

(c) 38

(d) 65

Ans: (b)

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44. Match List-I with List-II and select the correct answer using the codes given below the list List-I A) Loess B) Peat C) Alluvial soil D) Marl List-II 1. Deposited from suspension in running water 2. deposits of marine origin 3. deposits of wind 4. organic soil CODES: A

B

C

D

a) 3

4

2

1

b) 4

3

1

2

c)

4

3

2

1

d) 3

4

1

2

Ans: (d) 45. Match List-I (soils) with List-II (group symbols) and select the correct answer using codes given below the lists List-I A. B. C. D.

Clayey gravel Clayey sand Organic clay Silty sand

List-II 1. 2. 3. 4.

SM OH SC GC CODES:

a)

A

B

C

D

3

4

2

1

b)

4

3

1

2

c)

4

3

2

1

d)

3

4

1

2

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Ans: (c) 46. The value of porosity of a soil sample in which the total volume of soil grains is equal to twice the total volume of voids would be a) 75%

b) 66.66%

c) 50%

d) 33.33%

Ans: (c) 47. A soil has a liquid limit of 40% and plasticity index of 20% the plastic limit of the soil will be a) 20%

b) 30%

c) 40%

d) 60%

Ans: (a) 48. A sample of saturated sand has a dry unit weight of 18 KN/m3 and a specific gravity of 2.7. If density of water 10KN/m3, the void ratio of the soil sample will be a) 0.5

b) 0.6

c) 0.4

d) 0.9

Ans: e 1

27

49. A dry soil sample has equal amounts of soils and voids of volume. Its void ratio and porosity will be Void ratio

porosity (%)

a) 1.0

100%

b) 0.5

50%

c) 0.5

100%

d)1.0

50%

Ans: (d) 50. Based on grain distribution analysis, The D10, D30 and D60 values of a given soil are 0.23mm, 0.3mm and 0.41mm respectively. As per IS code, the soil classification will be a) SW

b) SP

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c) SM

d) SC

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Ans: The given soil is of size less than 4.75 mm and more than 75 . So the soil is sand

As

is less than 6 and

is not in between 1 to 3, the soil is SP

51. The plasticity index and the percentage of grain size finer than 2 microns of a clay sample of 25 and 15 respectively. Its activity ratio is a) 2.5

b) 1.67 c) 1.0

d) 0.6

Ans:

52. A soil sample having a void ratio of 1.3, water content of 50% and a specific gravity 2.60 is in a state of a) partial saturation

b) full saturation

c) over saturation

d) under saturation

Ans:

53. The natural void ratio of sand sample is 0.6 and its density index is 0.6. If its void ratio in the loosest state is 0.9, then the void ratio in the densest state will be a) 0.2

b) 0.3 c) 0.4

d) 0.5

Ans:

54. Which one of the following phase diagrams represents a clay at its

shrinkage limit?

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Ans: (b) 55. Which one of the following correctly represents the dry unit weight of a soil sample which has a bulk unit weight of at a moisture content of w%? a)

c)

b)

]

d)

Ans: (c) 56. Given that the coefficient of curvature = 1.4 D30 = 3mm, D10 = 0.6mm, based on this information of particle size distribution for use as a sub grade, this soil will be taken to be a) Uniformly graded sand b) Well-graded sand c) Very fine sand d) Poorly-graded sand Ans: 57. Which one of the following represents relative density of saturated sand deposit having moisture content of 25% if maximum and minimum void ratio of sand are 0.95 and 0.45 respectively and specific gravity of sand particles is 2.6? a) 40%

b) 50% c) 60%

d) 70%

Ans:

0.65 2.6

0.65 1

58. In a soil specimen, 70% particles are passing through 4.75mm IS sieve and 40% particles are passing through 75 μ IS sieve. Its uniformity

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coefficient is 8 and coefficient of curvature is 2. As per IS classification, this soil is classified as a) SP

b) GP

c ) SW

d) GW

Ans: (c) 59. The correct sequence of plasticity of minerals in soil in an increasing order is a) silica, kaolinite, illite, montmorillonite b) silica, kaolinite, montmorillonite, illite c) kaolinite, silica, illite, montmorillonite d) kaolinite,silica, montmorillonite, illite Ans: (a) 60. The predominant mineral responsible for shrinkage and swelling in black cotton soils is a) illite

b) kaolinite

c) mica

d) montmorillonite

Ans: (d) 61. Consistency as applied to cohesive soils in an indicator of its a) density c) shear strength

b) moisture content d) porosity

Ans: (b) 62. While computing the values of limits of consistency and consistency indices , it is found that liquidity index, has a negative value Consider the following comments on this value 1. 2. 3. 4.

Liquidity index cannot have a negative value and should be taken as zero Liquid index can have a negative value The soil tested is in semi solid state and stiff The soil tested in medium soft state.

Which of these statements are correct? a) 1 and 4 b) 2 and 4

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b)1 and 3 d) 2 and 3

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volume

Ans:

Water content

63. Two soil sample A and B have porosities =40% and respectively. What is the ratio of void ratios eA :eB? a) 2:3 Ans:

b) 3:2

c) 4:9

=60%

d) 9:4

64. Match List-I (densities) with List-II (expressions) and select the correct answer using the codes given below the lists: (Symbols G, e, γw and S stand for specific gravity of a soil grains , void ratio, unit weight of water and degree of saturation respectively) List-I a) Dry density

List-II 1) γw (G+Se)/(1+e)

b) Moist density

2) γwG/(1+e)

c) Submerged density 3) γw(G+e)/(1+e) 4) γw(G-1)/(1+e)

d) Saturated density A

B

C

D

a) 2

1

4

3

b) 2

3

4

1

c) 4

1

2

3

d) 4

3

2

1

Ans: (a) 65. What are the respective values of void ratio , porosity ratio and saturated density (in KN/m³) for a soil sample which has saturation moisture content of 20% and specific gravity of grains has 2.6? ( taken density of water has 10KN/ m³). a) 0.52, 1.08, 18.07 b) 0.52, 0.34, 18.07

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c) 0.77, 1.08, 16.64 d) 0.52, 0.34, 20.16 Ans:

5.2

0.52 1

26

66. Embankment fill is to be compacted at density of 18 KN/ m³.The soil of the barrow area is at a density of 15 KN/ m³. What is the estimated number of trips of 6 m³ capacity truck for hauling the soil required for compacting 100 m³ fill of the Embankment?(Assume that the soil in the barrow area and that in the Embankment are at the moisture content?) a) 14

b)18

c) 20 d) 23

Ans:

67. A clay sample has a void ratio 0.54 in dry state. the specific gravity of soil solids is 2.7. what is the shrinkage limit of soil? a) 8.5%

b) 10.0% c) 17.0%

d) 20.0%

Ans:

5.4 2.7

0. 54 1

Water content at just saturation is shrinkage limit.

68. Consider the following statements: 1. Mica is a clay mineral 2. Rock dust particles, even of clay size are non-plastic. 3. A particle of kaolinte is electrically changed. Which of these statements are correct? a) 1, 2 and 3

b) only 1and 2

c) Only 2 and 3 d) Only 1 and 3 Ans: (d)

69. Which of the following relation gives the value of degree of saturation S, in terms of unit Weight , water content w (as ratio) and specific gravity of soil solids Gs is unit weight of the water?

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Sub: Geotechnical Engineering a)

γ

b)

γ


c) γ

d) γ

Ans: (c)

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soil mechanics jh academy question.pdf

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