Soil mechanics miscellaneous Easy Questions and Answers | Page - 2

Soil mechanics miscellaneous

Which of the following statements is NOT correct?

1. Loose sand exhibits contractive behaviour upon shearing
1. Dense sand when under untrained condition, may lead to generation of negative pore pressure
1. Black cotton soil exhibits expansive behaviour
1. Liquefaction is the phenomenon where cohesion less soil near the downstream side of dams or sheet-piles loses its shear strength due to high upward hydraulic gradient

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Liquefaction is due to cyclic load and not due to high hydraulic gradient.

Correct Option: D

Liquefaction is due to cyclic load and not due to high hydraulic gradient.

Which of the following statements is TRUE for the relation between discharge velocity and seepage velocity?

1. Seepage velocity is always smaller than discharge velocity
1. Seepage velocity can never be smaller than discharge velocity
1. Seepage velocity is equal to the discharge velocity
1. No relation between seepage velocity and discharge velocity can be established

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Seepage velocity,
V_s = V
n

n(porosity) is always less than 1
∴ V_s > V (always)

Correct Option: B

Seepage velocity,
V_s = V
n

n(porosity) is always less than 1
∴ V_s > V (always)

If the water content of a fully saturated soil mass is 100%, the void ratio of the sample is

1. less than specific gravity of soil
1. equal to specific gravity of soil
1. greater than specific gravity of soil
1. independent of specific gravity of soil

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S = 100% (fully saturated)
e = wn
Sr

∴ e = 100G = G
100

Correct Option: B

S = 100% (fully saturated)
e = wn
Sr

∴ e = 100G = G
100

The relationship between porosity (η) specific yield (S_y) and specific retention (S_r) of an unconfined aquifer is:

1. S_y + S_r = η
1. S_y +η = S_r
1. S_r + η = S_r
1. S_y + S_r + η = 1

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Porosity (η), specific yield (S_y), specific retention (S_r) are related as;
S_y + S_r = η

Correct Option: A

Porosity (η), specific yield (S_y), specific retention (S_r) are related as;
S_y + S_r = η

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

1. SC
1. MI
1. CH
1. MH

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Since more than 50% n of sample pass through 75µ sieve, it is fine grained soil.
w_L = 45%
Q W_L > 35% and < 50%, it is intermediate compressible
(I) Equation of A-line
I_p = 0.73 (W_L – 20)
= 0.73 (45 – 20) = 18.25%
∴ I_p is below A line,
∴ it is silty soil (m)
∴ Group symbol is MI

Correct Option: B

Since more than 50% n of sample pass through 75µ sieve, it is fine grained soil.
w_L = 45%
Q W_L > 35% and < 50%, it is intermediate compressible
(I) Equation of A-line
I_p = 0.73 (W_L – 20)
= 0.73 (45 – 20) = 18.25%
∴ I_p is below A line,
∴ it is silty soil (m)
∴ Group symbol is MI