Phase Relations

JKSSB Junior Engineer (Civil) · Soil Mechanics · 14 practice questions with answers and explanations: 4 Easy, 10 Medium, 0 Hard.

Sample questions

Sample Easy question 1

The saturated unit weight of the same soil is about:

  1. 26.49 kN/m³
  2. 9.54 kN/m³
  3. 19.07 kN/m³
  4. 14.71 kN/m³
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Answer: C. γsat = (G + e) γw ÷ (1 + e) = 3.50 × 9.81 ÷ 1.8 = 19.07 kN/m³.

Sample Easy question 2

The specific gravity of most soil solids lies between:

  1. 3.5 and 4.5
  2. 1.0 and 1.5
  3. 2.6 and 2.8
  4. 0.5 and 1.0
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Answer: C. For quartz sand the value is about 2.65.

Sample Easy question 3

The void ratio of a soil can be:

  1. Greater than 1
  2. Only less than 1
  3. Only equal to 1
  4. Never above 0.5
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Answer: A. Soft clays and organic soils can have void ratios above 1, while porosity is always less than 1.

Sample Medium question 4

A soil has G = 2.7, e = 0.8 and w = 15%. The degree of saturation is:

  1. 15%
  2. 100%
  3. 29.6%
  4. 50.6%
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Answer: D. S = wG ÷ e = 0.15 × 2.7 ÷ 0.8 = 0.506.

Sample Medium question 5

The dry unit weight of a soil with G = 2.7 and e = 0.8 is about:

  1. 19.07 kN/m³
  2. 26.49 kN/m³
  3. 14.71 kN/m³
  4. 5.45 kN/m³
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Answer: C. γd = G γw ÷ (1 + e) = 2.7 × 9.81 ÷ 1.8 = 14.71 kN/m³.

Sample Medium question 6

A sand has a maximum void ratio of 0.9, a minimum void ratio of 0.45 and a natural void ratio of 0.55. Its relative density is:

  1. 22.2%
  2. 77.8%
  3. 50%
  4. 61.1%
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Answer: B. Dr = (emax − e) ÷ (emax − emin) = 0.35 ÷ 0.45 = 0.778.

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