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Permeability of Soils

15 questions. Tap an option to check it instantly, then read the solution.

Question 1Medium
If the velocity of flow of water through the soil is 0.01 cm/s and the piezometer readings at the end points A and B of soil sample are 10 cm and 5 cm, respectively. The distance between the points A and B is 20 cm. Find the coefficient of permeability of the soil sample.
Full explanation

Answer: B. 0.04 cm/s

i = (hA-hB)/L = (10-5)/20 = 0.25; K = v/i = 0.01/0.25 = 0.04 cm/s.

Question 2Easy
The coefficient of permeability has the same unit as that of
Full explanation

Answer: B. velocity

K has the same units as velocity (cm/s or m/s), since hydraulic gradient is dimensionless.

Question 3Hard
In a falling head test, the initial head level is 100 cm and the head level after 100 seconds is 10 cm. The area of cross-section of stand-pipe is 10 cm², and the area of cross-section of soil sample is 100 cm². Find the permeability of soil sample if the length of sample is 20 cm.
Full explanation

Answer: D. 0.046 cm/s

K = 2.303(aL/At)log10(h1/h2) = 2.303 x 0.02 x 1 = 0.046 cm/s.

Question 4Medium
Select the option that is correct regarding the following two statements, labelled as Assertion (A) and Reason (R), with respect to permeability of soil. Assertion (A): Permeability of soil continues to decrease with the increase in dry density of compacted soil. Reason (R): Soil and water are compressible in nature.
Full explanation

Answer: C. A is true, but R is false

Assertion is true (higher dry density -> lower permeability); Reason is false (soil/water are not compressible).

Question 5Easy
Which of the following laboratory methods is more suitable to determine the permeability of less permeable soils?
Full explanation

Answer: D. Falling head test

Falling head test suits low-permeability soils (silt, clay).

Question 6Medium
Select the option that is appropriate regarding the following two statements labelled Assertion and Reason Assertion: A loose, permeable, sandy soil has a higher infiltration capacity than that of a tight, clayey soil. Reason: A soil with poor under-drainage has a higher infiltration capacity.
Full explanation

Answer: D. Assertion is true, but Reason is false

Assertion is true (sand infiltrates faster than clay); Reason is false (good, not poor, drainage raises infiltration capacity).

Question 7Easy
In soil mechanics, what is Darcy constant?
Full explanation

Answer: B. Coefficient of permeability

Darcy constant = coefficient of permeability (K).

Question 8Easy
The law of flow of water through the soil was first studied by
Full explanation

Answer: C. Darcy

The law of flow of water through soil was first studied by Darcy.

Question 9Easy
The constant head permeability test is used for
Full explanation

Answer: C. coarse grained soil

Constant head test suits high-permeability, coarse-grained soil.

Question 10Medium
The infiltration capacity of soil does not depend on
Full explanation

Answer: C. Rain fall intensity

Infiltration capacity does not depend on rainfall intensity (that affects the rate, not the capacity).

Question 11Medium
Study the following statements and identify the correct option with respect to factors affecting permeability of soil medium. Statement A: Permeability is directly proportional to the viscosity of water and inversely proportional to its weight. Statement B: Degree of saturation of soil medium alters the permeability through soil.
Full explanation

Answer: D. Statement B is correct and A is incorrect

k is proportional to gamma_w/mu (A is incorrect); k increases with degree of saturation (B is correct).

Question 12Easy
The force per unit area that must be exerted in order to extract water from soil is known as......
Full explanation

Answer: C. capillary potential

Force per unit area to extract water from soil = capillary potential.

Question 13Easy
According to Darcy's law, in most of the soil (except coarse gravel), the pores are so small that the flow of water through them is always
Full explanation

Answer: D. Laminar

Flow through soil pores (except coarse gravel) is always laminar.

Question 14Easy
Which of the following soil type has the highest value of co-efficient of permeability?
Full explanation

Answer: A. Coarse sand

Coarse sand has the highest coefficient of permeability among common soils.

Question 15Medium
Which of the following is NOT the most common laboratory methods for determining the coefficient of permeability of soils?
Full explanation

Answer: A. Indirect determination from compaction test

Indirect determination from a compaction test is NOT a recognized lab method (consolidation test is).