Degree of Consolidation

Q. A layer of clay of 8 m thickness is located between two sand layers. The coefficient of consolidation of the clay is $5\times {10}^{-4}c{m}^2/sec$ . The fill material was placed over a very large area above the top sand layer . After 3 years, the percentage of additional pressure due to fill material will be carried by the soil grains at the middle of clay layer

1. 58%
2. 43.4%
3. 60.9%
4. 78.2%

Q. So long as the degree of consolidation (U) does not exceed 60% , its value after a time t is determined by the equation

1. $U=\frac{2}{d}\sqrt{\frac{C_v}{\pi t}}$
2. $U=\frac{2}{d}\sqrt{\frac{C_{v}t}{\pi }}$
3. $U=2d\sqrt{\frac{C_v}{\pi t}}$
4. $U=2d\sqrt{\frac{C_v\cdot t}{\pi }}$

Q. The time taken to construct building was from April 1992 to September 1993. In September 1996, the average settlement was found to be 5.16 cm. If the ultimate settlement is estimated to be 25 cm, then the settlement in January 1997 would have been

1. 6 cm
2. 7 cm
3. 8 cm
4. 9 cm

Q. If the time required for 60% consolidation of a remoulded soil sample of clay with single drainage is 't', then what is the time required to consolidate the same sample of clay with the same degree of consolidation but with double drainage?

1. 4t
2. 2t
3. t/2
4. t/4

Q. The change that take place during the process of consolidation of a saturated clay would include

1. an increase in pore water pressure and an increase in effective pressure
2. an increase in pore water pressure and a decrease in effective pressure
3. a decrease in pore water pressure and a decrease in effective pressure
4. a decrease in pore water pressure and an increase in effective pressure

Q. A 10 m thick clay layer is resting over a 3 m thick sand layer and is submerged. A fill of 2 m thick sand with unit weight of 20$kN/m^3$ is placed above the clay layer to accelerate the rate of consolidation of the clay layer. Coefficient of consolidation of clay is $9\times {10}^{-2}{m}^2/year$ and coefficient of volume compressibility of clay is $2.2\times {10}^{-4}{m}^2/kN$. Assume Taylor's relations between time factor and average degree of consolidation.


The settlement (in mm, round off to two decimal places) of the clay layer, 10 years after the construction of the fill, is

1. 18.83

Q. Construction of a new building founded on a clayey soil was completed in January 2010. In January 2014, the average consolidation settlement of the foundation in clay was recorded as 10 mm. The ultimate consolidation settlement was estimated in design as 40 mm. Considering double drainage to occur at the clayey soil site, the expected consolidation settlement in January 2019 (in mm, round off to the nearest integer) will be

1. 15

Q. A clay layer 3 m deep is sandwiched by a pervious material. The soil reaches 90% consolidation in 3 years. At another site, the same clay layer is bounded by impervious boundary at the bottom and sand at the top. What is the time taken by this layer to reach 90% settlement?

1. 9 years
2. 12 years
3. 15 years
4. 21 years

Q. The identical clay samples of the same size, designated as A and B are subjected to consolidation test under identical loading conditions. Drainage takes place through one face in sample A and through both the faces in sample B. 50% consolidation of sample A occurs in 10 minutes. The time required for 50% consolidation to occur in sample B will be

1. 40 minutes
2. 10 minutes
3. 5 minutes
4. 2.5 minutes