Determination of Coefficient of Permeability

Q. Due to rise in temperature, the viscosity and unit weight of percolating fluid are reduced to 70% and 90% respectively. Other things being constant, the change in coefficient of permeability will be

1. 20.0%
2. 28.6%
3. 63.0%
4. 77.8%

Q. In a falling head permeability test the initial head of 1.0 m dropped to 0.35 m in 3 hours, the diameter of the stand pipe being 5mm. The soil specimen was 200 mm long and of 100 mm diameter. The coefficient of permeability of the soil is:

1. 4.86 $\times$${10}^{-5}cm/s$
2. 4.86 $\times$${10}^{-6}cm/s$
3. 4.86 $\times$${10}^{-7}cm/s$
4. 4.86 $\times$${10}^{-8}cm/s$

Q. If during a permeability test on a soil sample with a falling head permeameter, equal time intervals are noted for drop of head from ${}^{\prime }{h}_1^{\prime }to{}^{\prime }{h}_2^{\prime }$ and again from ${}^{\prime }{h}_2^{\prime }to{}^{\prime }{h}_3^{\prime }$, then which one of the following relations would hold good?

1. $h_3^2=h_1{h}_2$
2. $h_1^2=h_2{h}_3$
3. $h_2^2=h_1{h}_3$
4. $(h_1-h_2)=(h_2-h_3)$

Q. The coefficient of permeability of a soil is 5 $\times$ ${10}^{-5}$ cm/sec for a certain pore fluid. If the viscosity of the pore fluid is reduced to half, the coefficient of permeability will be

1. $5\times {10}^{-5}cm/sec$
2. $10\times {10}^{-5}cm/sec$
3. $2.5\times {10}^{-5}cm/sec$
4. $1.25\times {10}^{-5}cm/sec$

Q. A 30 cm diameter well completely penetrates a confined aquifer of uniform thickness 30 m as shown in the below figure.

If steady stage discharge from the well is 3520 litres/min, coefficient of permeability would be m/day.

1. 8.44
2. 3.29
3. 5.0
4. 11.12

Q. In a two-layer soil system, the top soil and bottom soil are of same thickness but the coefficient of permeability of the top soil is twice that of the bottom soil of coefficient of permeability 'k'. When horizontal flow occurs, the equivalent coefficient of permeability of the system will be

1. 2k
2. 1.5k
3. 1.25k
4. 1.2k

Q. In a falling head permeability test on a sample 12.2 cm high and 44.41 cm${}^2$ in cross - sectional area, the water level in a standpipe of 6.25 mm internal diameter dropped from a height of 75 cm to 24.7 cm in 15 minutes. Find the coefficient of permeability

1. $1.04\times {10}^{-3}cm/s$
2. $2.04\times {10}^{-4}cm/s$
3. $1.04\times {10}^{-4}cm/s$
4. None of these

Q. In a constant head permeameter with cross-section area of 10$c{m}^2$ , when the flow was taking place under a hydraulic gradient of 0.5, the amount of water collected in 60 s is 600 cc. The permeability of the soil is

1. 0.002 cm/s
2. 0.25 cm/s
3. 0.2 cm/s
4. 2.0 cm/s

Q. A constant-head permeability test was conducted on a soil specimen under a hydraulic gradient of 2.5. The soil specimen has specific gravity of 2.65 and saturated water content of 20%. If the coefficient of permeability of the soil is 0.1 cm/s, the seepage velocity (in cm/s, round off to two decimal places) through the soil specimen is

1. 0.72

Q. In a falling head permeability test on a soil, the time taken for the head to fall from $h_0$ to $h_1$ is t. The test is repeated with same initial head $h_0$, the final head h' is noted in time t/2. Which one of the following equations gives the relation between h'. $h_0$ and $h_1$?

1. $h^{\prime }=h_0/h_1$
2. $h^{\prime }=\sqrt{h_0/h_1}$
3. $h^{\prime }=h_0{h}_1$
4. $h^{\prime }=\sqrt{h_0{h}_1}$

Q. Two soil specimens with identical geometric dimensions were subjected to falling head permeability tests in the laboratory under identical conditions. The fall of the water head was measured after an identical time interval. The ratio of initial to final water heads for the test involving the first specimen was 1.25. If the coefficient of permeability of the second specimen is 5-times that of the first, the ratio of initial to final water heads in the tests involving the second specimen is

1. 3.05
2. 3.80
3. 4.00
4. 6.25

Q. Consider the following statements:
1. Coarse sand is more than a million times permeable than a high plasticity clay.
2. The permeability depends on the nature of soil and not on properties of liquid flowing through soil.
3. If a sample of sand and a sample of clay have the same void ratio, both samples will exhibit the same permeability.
4. Permeability of soil decreases as the effective stress acting on the soil increases.
Which of these statements are correct?

1. 1 and 2
2. 1 and 3
3. 1 and 4
4. 2 and 3

Q. The porosity of a certain soil sample was found to be 80% and its specific gravity was 2.7; the critical hydraulic gradient will be estimated as

1. 0.34
2. 0.92
3. 1.0
4. 1.5

Q. The following data were obtained when a sample of medium sand was tested in a constant head permeameter:
Cross-section area of sample : 100 cm${}^2$
Hydraulic gradient : 10
Discharge collected : 10 cc/s
The coefficient of permeability of the sand is

1. 0.1 m/s
2. 0.01 m/s
3. 1 $\times$ 10${}^{-4}$ m/s
4. 1 $\times$ 10${}^{-8}$ m/s

Q.

In a falling head permeameter test on a silty clay sample, the following results were obtained;
sample length 120mm; sample diameter 80mm; initial head $1200mm$; final head $400mm$; time for fall in head $6$ minutes stand pipe diameter $4mm$. The coefficient of permeability of the soil is_____ $\times {10}^{-4}$ mm/sec

1. 9.155

Q. Match List-I (Soil description) with List-II (Coefficient of permeability, mm/s) and select the correct answer using the codes given below the lists:
List-I
A. Gravel
B. Clay silt admixtures
C. Loess
D. Homogeneous clays
List-II
1. > 1
2. 10${}^{-2}$ to 10${}^{-4}$
3. < 10${}^{-6}$
4. 10${}^{-4}$ to 10${}^{-6}$
Codes:
A B C D

1. 4 1 3 2
2. 1 4 3 2
3. 4 1 2 3
4. 1 4 2 3

Q. Constant head permeability tests were performed on two soil specimens, S1 and S2. The ratio of height of the two $(L_{S1}:L_{S2})$ is 1.5, the ratio of the diameter of specimens $(D_{S1}:D_{S2})$ is 0.5, and the ratio of the constant head $(h_{S1}:h_{S2})$ applied on the specimens is 2.0. If the discharge from both the specimens is equal, the ratio of the permeability of the soil specimens $(k_{S1}:k_{S2})$ is

1. 3

Q. Consider the following statements:
1. Constant head permeameter is best suited for determination of coefficient of permeability of highly impermeable soils.
2. Coefficient of permeability of a soil mass decreases with increase in viscosity of the pore fluid
3. Coefficient of permeability of soil mass increases with increase in temperature of the pore fluid.
Which of these statements are correct?

1. 1 and 2
2. 1 and 3
3. 2 and 3
4. 1, 2 and 3

Q. An extended layer of soil with homogeneous rounded grains has 10% of the material finer than 0.07 mm. The constant to be adopted to determine its permeability has been recommended as 750. What is its permeability?

1. 30.18m/day
2. 317.54 m/day
3. 31752m/day
4. 31.752 m/day

Q. A dam is to be constructed on a sandy soil which has coefficient of permeability $10\times {10}^{-4}cm/sec$ in horizontal direction $2.5\times {10}^{-4}cm/sec$ in vertical direction. The dam is expected to impound 7.5 m of water. Flow net drawn on transformed section yields flow channels as '6' and drops are 15 only. The seepage loss per metre length of dam if water on downstream is 0.5 m

1. $14\times {10}^{-6}{m}^2/s$
2. $15\times {10}^{-6}{m}^2/s$
3. $14\times {10}^{-6}{m}^2/s$
4. $7\times {10}^{-6}{m}^2/s$

Q. Consider the following statements:
1. Constant head permeameter is best suited for determination of coefficient of permeability of highly impermeable soils.
2. Coefficient of permeability of a soil mass decreases with increase in viscosity of the pore fluid
3. Coefficient of permeability of soil mass increases with increase in temperature of the pore fluid.
Which of these statements are correct?

1. 1 and 2
2. 1 and 3
3. 2 and 3
4. 1, 2 and 3

Q. Match List-I and with List-II and select the correct answer using the codes given below the lists

List-I

(A) Constant head permeability test

(B) Consolidation test

(C) Pycnometer test

(D) Negative skin friction

List - II

1. Pile foundation

2. Specific gravity

3. Clayey soil

4. Sand

1. A - 4, B - 3, C - 2, D - 1
2. A -4, B - 2, C - 3, D - 1
3. A - 3, B - 4, C - 2, D - 1
4. A - 4, B - 1, C - 2, D - 3

Q. In a two-layer soil system, the top soil and bottom soil are of same thickness but the coefficient of permeability of the top soil is twice that of the bottom soil of coefficient of permeability 'k'. When horizontal flow occurs, the equivalent coefficient of permeability of the system will be

1. 2k
2. 1.5k
3. 1.25k
4. 1.2k