QUIZ:CIVIL ENGINEERING (9-april-2020)

Quiz: Civil Engineering
Exam: UPSSSC-JE
Topic: Permeability of Soil

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. Darcy’s law is not applicable for flow in –
(a) Fine sand
(b) Clays
(c) Silts
(d) Gravels
L1Difficulty 1
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q2. A flow net may be utilized for the determination of:
(a) Hydrostatic pressure only
(b) Seepage only
(c) Exit gradient only
(d) All of the above
L1Difficulty 2
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q3. If permeability of a soil at the void ratio of e_1 and e_2 are k_1 and k_2 then which of the following relation is correct?
(a) k_1/ k_2=(1+e_1 ) / (1+e_2)
(b) k_1/ k_2=(1-e_1) / (1-e_2)
(c) k_1/ k_2=e_1 / e_2
(d) None of these
L1Difficulty 3
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q4. If the coefficient of permeability for the soil is 10^(-7)cm/sec, then the soil can be classified as
(a) clay
(b) silt
(c) sand
(d) gravel
L1Difficulty 2
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q5. The constant head permeameter is suitable for:
(a) Silty soil
(b) Organic soil
(c) Coarse grained soils
(d) Clay
L1Difficulty 2
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q6. A soil has a discharge velocity of 6 × 10^(-7) m/s and void ratio of 0.5. What is its seepage velocity?
(a) 3 × 10^(-7) m/s
(b) 6 × 10^(-7) m/s
(c) 12 × 10^(-7) m/s
(d) 18 × 10^(-7) m/s
L1Difficulty 3
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q7. The property of a soil which permits water to percolate through it, is called
(a) Capillarity
(b) Consolidation
(c) Permeability
(d) Moisture content
L1Difficulty 2
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q8. A fine grained soil has:
(a) Low permeability and high compressibility
(b) High permeability and low compressibility
(c) Low permeability and low compressibility
(d) High permeability and high compressibility
L1Difficulty 2
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q9. The hydraulic head that would produce a quick sand condition in a sand stratum of thickness 1.8m, specific gravity 2.65 and void ratio 0.65 is equal to:
(a) 1.0 meter
(b) 1.2 meter
(c) 1.6 meter
(d) 1.8 meter
L1Difficulty 4
QTags Geo Tech Engineering
QCereator Anubhav Gupta

Q10. Coefficient of permeability of soil
(a) Does not depend upon temperature
(b) Increases with increase in temperature
(c) Increases with decreases in temperature
(d) None of the above
L1Difficulty 2
QTags Geo Tech Engineering
QCereator Anubhav Gupta

SOLUTION

S1. Ans.(d)
Sol. Darcy law – For laminar flow is saturated soil mass velocity is directly proportional to its hydraulic gradient.
▭(V α i )
▭(V α ki )
K → coefficient of permeability
→ Darcy law is not applicable for flow of gravels. Because in gravel flow is not laminar.

S2. Ans.(d)
Sol. Application of flow net –
Seepage discharge
Seepage pressure
Hydrostatic pressure
Exit gradient

S3. Ans.(d)
Sol. according to kozney karman equation
Permeability (k) =1/Kk (r_w/μ)(e^3/(1+e)) d^2
▭(k α e^2 )
▭(K_1/K_2 α (e_1^2)/(e_2^2 ))

S4. Ans.(a)
Sol.
Soil Coefficient of permeability (Cm/sec)
Gravel
Sand
Silt
Clay > 1
1 – 10^(-3)
10^(-3)- 10^(-6)
< 10^(-6)

S5. Ans.(c)
Sol. the constant head parameter is suitable for determination of permeability in coarse grained soil.
▭(K=2.303 aL/At log_10 h_1/h_2 )

S6. Ans.(d)
Sol. discharge velocity (V) = 6 × 10^(-7) m/s
Void ratio (e) = 0.5
Porosity (n) = e/(1+e)
= 0.5/(1+0.5)
= 0.5/1.5
=0.33
Seepage velocity (V_s ) = V/n
=(6×10^(-7))/0.33
V_s=18.18× 10^(-7) m/sec

S7. Ans.(c)
Sol. the property of a soil which permits water to percolate through it is called permeability.
S8. Ans.(a)
Sol. fine grained soil has low permeability & high compressibility.
S9. Ans.(d)
Sol. thickness (t) = 1.8 m
G = 2.65
Void ratio (e) = 0.65
For quick sand condition –
Critical hydraulic gradient (i_c ) = (G-1)/(1+e)
(G-1)/(1+e)=∆h/t
(2.65-1)/(1+0.65)=∆h/1.8
1.65/1.65=∆h/1.8
▭(∆h=1.8 meter)
S10. Ans.(b)
Sol. Coefficient of permeability of soil is directly proportional to temperature

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