Soil Mechanics - Seepage of Soils

1. A sand deposit has a porosity of 1/3 and its specific gravity is 2.5. The critical hydraulic gradient to cause sand boiling in the stratum will be
(a) 1.5
(b) 1.25
(c) 1.0
(d) 0.75 (IES 1997)
Hint: i = (G - 1)/(1 - n)

2. According to Darcy’s law for flow through porous media, the velocity is proportional to
(a) effective stress
(b) hydraulic gradient
(c) cohesion
(d) stability number (GATE 1997)

3. Seepage takes place around/through
(a) sheet pile walls
(b) under masonry dams
(c) earth dams
(d) all these

4. Laplace’s equation for two dimensional flow is
(a) \frac{{{\partial ^2}h}}{{\partial {x^2}}} + \frac{{{\partial ^2}h}}{{\partial {z^2}}} = 0
(b) \frac{{{\partial ^3}h}}{{\partial {x^3}}} + \frac{{{\partial ^3}h}}{{\partial {z^3}}} = 0  
(c) \frac{{{d^2}h}}{{d{x^2}}} + \frac{{{d^2}h}}{{d{z^2}}} = 0  
(d) \frac{{{d^3}h}}{{d{x^3}}} + \frac{{{d^3}h}}{{d{z^3}}} = 0  

5. If points with equal head are joined then, the line so obtained is called
(a) flow line
(b) flow channel
(c) equipotential line
(d) none of these

6. Flow net is set(s) of
(a) flow lines
(b) equipotential lines
(c) flow lines and equipotential lines
(d) none of these

7. The solution of Laplace’s equation is represented by
(a) flow lines
(b) equipotential lines
(c) both (a) and (b)
(d) flow net

8. In a flow net, flow lines and equipotential lines are
(a) parallel
(b) intersect each other at an angle at 450
(c) intersect each other at an angle at 600
(d) orthogonal

9. Which of the following is not true?
(a) quantity of seepage in each flow path(channel) is same
(b) drop in  head between adjacent equipotential lines is same
(c) It is very difficult to construct a flow net in which all the fields are elementary squares
(d) quantity of flow can be computed by using flow net

10. flow net can be used to
(a) compute quantity of flow
(b) compute uplift pressure
(c) investigating unstable conditions
(d) all these

Answers

    1. (c)    2. (b)    3. (d)    4. (a)    5. (c)
    6. (c)    7. (d)    8. (d)    9. (c)    10. (d)

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These questions are taken from the book "Objective Questions (Civil Engineering)". The Kindle edition of this book is available at just ₹ 99/- only! 

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