Compaction and Consolidation - Geotechnical Engineering - Civil Engineering Previous Year Questions

1

2014 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2014 [Session 1]

The following data are given for the laboratory sample.

$\sigma_0' = 175 \text{ kPa}$ ; $e_0 = 1.1$ ; $\sigma_0' + \Delta \sigma_0' = 300 \text{ kPa}$ ; $e = 0.9$

If thickness of the clay specimen is 25 mm, the value of coefficient of volume compressibility is ________ $\times 10^{-4} \text{ m}^2/\text{kN}$

A

B

C

D

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2

2015 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2015 [Session 1]

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:
\[ T_v = \begin{cases} \left( \frac{\pi}{4} \left( \frac{U}{100} \right)^2 \right) & \text{for } U \leq 60\% \\ \left( 1.781 - 0.933 \log_{10}(100 - U) \right) & \text{for } U > 60\% \end{cases} \]
where \(T_v\) is the time factor and \(U\) is the degree of consolidation in %.
If the coefficient of consolidation of the layer is 0.003 cm²/s, the deposit will experience a total of 50 mm settlement in the next _______________ years.

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3

2015 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2015 [Session 2]

A 4 m thick layer of normally consolidated clay has an average void ratio of 1.30. Its compression index is 0.6 and coefficient of consolidation is 1 m²/yr. If the increase in vertical pressure due to foundation load on the clay layer is equal to the existing effective overburden pressure, the change in the thickness of the clay layer is __________ mm

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4

2016 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2016 [Session 1]

An undisturbed soil sample was taken from the middle of a clay layer (i.e., 1.5 m below GL), as shown in figure. The water table was at the top of clay layer. Laboratory test results are as follows:
Natural water content of clay : 25%
Preconsolidation pressure of clay : 60 kPa
Compression index of clay : 0.50
Recompression index of clay : 0.05
Specific gravity of clay : 2.70
Bulk unit weight of sand : 17 kN/m³

A compacted fill of 2.5 m height with unit weight of 20 kN/m³ is placed at the ground level.

Assuming unit weight of water as 10 kN/m³, the ultimate consolidation settlement (expressed in mm) of the clay layer is __________

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5

2016 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2016 [Session 2]

The results of a consolidation test on an undisturbed soil, sampled at a depth of 10 m below the ground level are as follows:

Saturated unit weight : \( 16\ kN/m^3 \)
Pre-consolidation pressure : \( 90\ kPa \)

The water table was encountered at the ground level. Assuming the unit weight of water as \( 10\ kN/m^3 \), the over-consolidation ratio of the soil is

A

0.67

B

1.50

C

1.77

D

2.00

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6

2016 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2016 [Session 2]

OMC-SP and MDD-SP denote the optimum moisture content and maximum dry density obtained from standard Proctor compaction test, respectively. OMC-MP and MDD-MP denote the optimum moisture content and maximum dry density obtained from the modified Proctor compaction test, respectively. Which one of the following is correct?

A

OMC-SP < OMC-MP and MDD-SP < MDD-MP

B

OMC-SP > OMC-MP and MDD-SP < MDD-MP

C

OMC-SP < OMC-MP and MDD-SP > MDD-MP

D

OMC-SP > OMC-MP and MDD-SP > MDD-MP

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7

2017 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2017 [Session 2]

Let \(G\) be the specific gravity of soil solids, \(w\) the water content in the soil sample, \(\gamma_w\) the unit weight of water, and \(\gamma_d\) the dry unit weight of the soil. The equation for the zero air voids line in a compaction test plot is

A

\(\gamma_d = \frac{G\gamma_w}{1 + Gw}\)

B

\(\gamma_d = \frac{G\gamma_w}{Gw}\)

C

\(\gamma_d = \frac{Gw}{1 + \gamma_w}\)

D

\(\gamma_d = \frac{Gw}{1 - \gamma_w}\)

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8

2018 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2018 [Session 2]

The compression curve (void ratio, e vs. effective stress, \(\sigma_v'\)) for a certain clayey soil is a straight line in a semi-logarithmic plot and it passes through the points (e = 1.2; \(\sigma_v'\) = 50 kPa) and (e = 0.6; \(\sigma_v'\) = 800 kPa). The compression index (up to two decimal places) of the soil is ______

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9

2019 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2019 [Session 2]

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 ______

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10

2020 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2020 [Session 2]

A one-dimensional consolidation test is carried out on a standard 19 mm thick clay sample. The oedometer’s deflection gauge indicates a reading of 2.1 mm, just before removal of the load, without allowing any swelling. The void ratio is 0.62 at this stage. The initial void ratio (round off to two decimal places) of the standard specimen is __________.

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11

2020 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2020 [Session 2]

A footing of size 2 m × 2 m transferring a pressure of 200 kN/m², is placed at a depth of 1.5 m below the ground as shown in the figure (not drawn to the scale). The clay stratum is normally consolidated. The clay has specific gravity of 2.65 and compression index of 0.3. Considering 2:1 (vertical to horizontal) method of load distribution and \(\gamma_w = 10\) kN/m³, the primary consolidation settlement (in mm, round off to two decimal places) of the clay stratum is __________.

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12

2022 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2022 [Session 2]

A saturated compressible clay layer of thickness h is sandwiched between two sand layers, as shown in the figure. Initially, the total vertical stress and pore water pressure at point P, which is located at the mid-depth of the clay layer, were 150 kPa and 25 kPa, respectively. Construction of a building caused an additional total vertical stress of 100 kPa at P. When the vertical effective stress at P is 175 kPa, the percentage of consolidation in the clay layer at P is __________. (in integer)

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13

2024 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2024 [Session 1]

An embankment is constructed with soil by maintaining the degree of saturation as 75% during compaction. The specific gravity of soil is 2.68 and the moisture content is 17% during compaction. Consider the unit weight of water as \( 10 \, \text{kN/m}^3 \). The dry unit weight (in \( \text{kN/m}^3 \)) of the compacted soil is __________ (rounded off to 2 decimal places).

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14

2024 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2024 [Session 1]

The total primary consolidation settlement (\(S_c\)) of a building constructed on a 10 m thick saturated clay layer is estimated to be 50 mm. After 300 days of the construction of the building, primary consolidation settlement was reported as 10 mm. The additional time (in days) required to achieve 50% of \(S_c\) will be __________ (rounded off to the nearest integer).

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15

2025 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2025 [Session 2]

A 6 m thick clay stratum has drainage at both its top and bottom surface due to the presence of sand strata. The time to complete 50% consolidation is 2 years. The coefficient of volume change (*m*_v) is 1.51×10⁻³ m²/kN and unit weight of water is 9.81 kN/m³.
The coefficient of permeability (in m/year) is ______ (*round off to three decimal places*).

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16

2008 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2008

Compaction by vibratory roller is the best method of compaction in case of

A

moist silty sand

B

well graded dry sand

C

clay of medium compressibility

D

silt of high compressibility

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17

2008 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2008

A saturated clay stratum draining both at the top and bottom undergoes 50 percent consolidation in 16 years under an applied load. If an additional drainage layer were present at the middle of the clay stratum, 50 percent consolidation would occur in

A

2 years

B

4 years

C

8 years

D

16 years

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18

2009 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2009

Using the properties of the clay layer derived from the above question, the consolidation settlement of the same clay layer under a square footing (neglecting its self weight) with additional data shown in the figure below (assume the stress distribution as 1H:2V from the edge of the footing and \( \gamma_w = 10 \, \text{kN/m}^3 \) ) is

A

32.78 mm

B

61.75 mm

C

79.5 mm

D

131.13 mm

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19

2010 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2010

In a compaction test, G, w, S and e represent the specific gravity, water content, degree of saturation and void ratio of the soil sample, respectively. If \(\gamma_w\) represents the unit weight of water and \(\gamma_d\) represents the dry unit weight of the soil, the equation for zero air voids line is

A

\(\gamma_d = \frac{G \gamma_w}{1 + Se}\)

B

\(\gamma_d = \frac{G \gamma_w}{1 + Gw}\)

C

\(\gamma_d = \frac{G w}{e + \gamma_w S}\)

D

\(\gamma_d = \frac{G w}{1 + Se}\)

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20

2010 · Civil Engineering · Geotechnical Engineering · Compaction and Consolidation

Civil Engineering (CE) 2010

The e-log p curve shown in the figure is representative of

A

Normally consolidated clay

B

Over consolidated clay

C

Under consolidated clay

D

Normally consolidated clayey sand

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