Determination of Coefficient of Consolidation

Q. A 1 m thick layer of saturated clay, drained at both faces, settles by 10 cm in one year. If a thin layer of pervious soil is introduced in the middle of this layer, then what will be the period during which the settlement of 10 cm will be completed?

1. 4 years
2. 0.5 years
3. 0.25 years
4. 2 years

Q. Consider the following statements:

1. Mathematically speaking, the time taken for 100% consolidation is infinite.
2. The time factor for a particular average degree of consolidation depends upon the distribution of initial excess hydrostatic pressure.
3. Secondary consolidation obeys Terzaghi's one-dimensional theory of consolidation

Which of these statements are correct?

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

Q. A 20 m thick clay layer is sandwiched between a silty sand layer and a gravelly sand layer. The layer experiences 30 mm settlement in 2 years.

Given :

$T_V=\{\begin{array}{cc}\frac{\pi }{4}{\left(\frac{U}{100}\right)}^2& forU\le {60}^{\circ {/}_{\circ }}\\ 1.784-0.933lo{g}_{10}(100-U)& U>{60}^{\circ {/}_{\circ }}\end{array}$



Where $T_V$ is the time factor and U is the degree of consolidation in %

If the coefficient of consolidation of the layer is $0.003c{m}^2/s$, the deposit will experience a total of 50 mm settlement in the next _____ years.

1. 4.43

Q. A 3 m thick clay layer is subjected to an initial uniform pore pressure of 145 kPa as shown in the figure.



For the given ground conditions the time (in days, rounded to the nearest integer) required for 90% consolidation would be

1. 1771

Q. When a stress of 180 kPa is applied on a saturated clay layer drained at both ends, 40% consolidation occurs in 16 years. If an additional drainage layer is assumed to be present at the middle of the clay layer, 40% consolidation could occur in years.

1. 4 years
2. 8 years
3. 16 years
4. 64 years