QUESTION BANK
Semester : III sem (Civil Engg.) ,
Subject : Geotechnical Engineering - I
UNIT-I
Q.1. Discuss the origin of soil.
Q.2. Briefly describe the processes of soil formation and differentiate between
‘residual’ and ‘transported’ soils.
Q.3. Define the following terms
i) Void ratio ii) porosity iii) Degree of saturation iv) Specific gravity
Q.4. Explain the terms Bentonite, Black cotton soil and hardpan.
Q.5. Establish the expression for bulk unit weight for soil in terms specific
gravity, void ratio and degree of saturation.
Q.6. With the help of phase diagram prove that:
Sr.e = w.G
Q.7. A partially saturated soil from an earth fill has a natural water content of
19% and bulk unit weight of 19.33 kN/m3. Assuming the specific gravity
of soil solids as 2.6,compute the degree of saturation and void ratio. If
subsequently the soil gets saturated, Determine the dry unit weight and
saturated unit weight.
Q.8. In an earthen embankment under the bulk unit weight of 16.5 kN/m3 at
water content of 11%.If the water content is to be raised to 15%; compute
the quantity of water required to be added per cubic meter of soil. Assume
no change in the void ratio.
Q.9
The following observations were obtained in field density test:
i) Wt. of core cutter
1060gm
ii) Volume of core cutter
995 cm3
iii) Wt. of cutter + wet soil
3030 gm
iv) Water content of soil
16%
Determine dry unit weight, void ratio and degree of saturation of the soil
in its field condition. Assume the specific gravity of soil = 2.7
UNIT-II
Q.1. Explain Index properties
Q.2. Write note on water content and its determination.
Q.3. What do you understand by the term ‘Consistency of soil’? Explain the
different states of consistency in detail.
Q.4. Define the following term (any two)
i) Plasticity index
ii) Flow index
iii) Liquidity index.
Q.5. Sketch typical grain size distribution curves for
i) Well graded soil
ii) Uniform silty sand
iii) Poorly graded soil
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Q.6.
Q.7.
Q.8.
Q.9.
How would you calculate the following from these curve
a) Effective size
b) Uniformity coefficient
c) Coefficient of curvature
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Define Liquid Limit and Plastic Limit. Determine the value of liquid limit
of a soil from the following test data.
Number of blows:- 38
34
20
12
Water content:16
17
20
22
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The plastic limit and liquid limit of a soil are 32% and 45% respectively.
The percentage volume change from the liquid limit to the dry state is
36% of the dry volume. Similarly, the percentage volume change from the
plastic limit to the dry state is 24% of the dry volume. Determine the
shrinkage limit and shrinkage ratio.
Explain I.S. classification of solids with the help of plasticity chart.
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Write note on
i) Relative density and its practical application
ii) Sand replacement method
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UNIT-III
Q.1. State and explain the Darcy’s law of permeability. Comment on its
Limitations.
Q.2. Enlist the factors affecting permeability of soil. Explain any two factors
Q.3. Following data refers to the falling head permeability test conducted on
sandy soil .
i) Diameter of stand pipe
= 2.5 X 10-4 m2
ii) Area of cross section of soil sample
= 22 X 10-4 m2
iii) Length of sample
= 17 cm
iv) Time required to fall head from 0.25m 0.10m is 6 seconds.
Compute the coefficient of permeability in meter per hour.
Q.4. The permeability of soil is 1 X 10-3 cm/sec at void ratio of 0.4. Estimate
the permeability if the soil is placed at void ratio of 0.6.
Q.5. Derive the expression for falling head permeability test.
Q.6. Determine the ratio of average permeability coefficient parallel to the
bedding plane to that of perpendicular to the bedding plane. For a soil
sample consisting of three layers having thickness in the ratio of 1:1.5:2.
the permeability coefficient for second layer is twice the first and third is
twice that of second.
Q.7. What is properties and application of flow net?
Q.8. Explain ‘Quick sand condition’ Give the expression for critical hydraulic
Gradient along with its significance.
Q.9. Explain the application of flow net.
Q.10. What is a square flow net? Prove that for a square flow net the discharge
through each flow channel is same.
Q.11 Establish the relationship between discharge velocity (V) and the seepage
Velocity (Vs) for a soil with void ratio (e).
Q.12. An earth dam is built on an impervious foundation with a horizontal filter
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At the base near the toe. the permeability of soil in the horizontal and
vertical direction are 3 X 10-2 mm/sec. and 1.5 X 10-2 mm/sec.
respectively. The full reservoir level is 30m above the filter. A flow
net constructed for the transformed section of the dam, consist of 4
flow channels and 16 head drops. Estimate the seepage loss per meter
length of the dam.
UNIT- IV
Q.1. State and explain the assumptions of Boussinesq theory.
Q.2
Explain the pressure bulb and its significance.
Q.3. Explain
i) Stress isobar
ii) Vertical stress distribution on a horizontal plane.
Q.4. Write short note on construction of isobars
Q.5. A rectangular area of 2 m X 4m carries u.d.l. of 10t /m2 at the ground
surface. Estimate the vertical pressure at the depth of 8m vertically below
a corner of the loaded area.
Q.6. A circular area is loaded with a uniform load intensity of 100 kN/m2 at
ground surface. Calculate the vertical pressure at a point P so situated on
the vertical line through the centre of loaded area that the area subtends
an angle 90O at P. use the Boussinesq analysis.
Q.7. Two column A and B are standing 5m apart. Load transferred through
them may be taken as point load. Through column A a load of 400 kN
are acting. Calculate the resultant vertical pressure due to these load on a
horizontal plane 2m below the ground surface at points vertically below
the column A and B.
UNIT-V
Q.1
What do you understand by the term compaction? Explain how you do
achieve field compaction control.
Q.2. Explain the following term (any two)
i) Vergin compaction curve
ii) Compression Index
iii) Degree of compaction
Q.3. Differentiate between compaction and consolidation
Q.4
State and explain the factors affecting rate of compaction
Q.5. Discuss equipment used for compaction is field with their suitability
With respect to type of soil.
Q.6
Following observations were made in a standard proctor test:-
Trial No
1
2
3
4
Mass of wet soil (Kg)
1.70
1.89
2.03
1.99
Water content (%)
7.7
11.5
14.6
17.5
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5
6
1.96
1.92
19.7
21.2
Volume of mould = 950 CC ; G = 2.65
Plot the graph and determine MDD and OMC. Give your inference on the
result obtained.
Q.7. Explain the ‘square root of time fitting’ method for determination of
coefficient of consolidation
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Q.8. Define the ‘pre-consolidation pressure’ Describe the procedure for
determining the pre-consolidation pressure
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Q.9
Explain the log of time method for consolidation
Q.10. Assumptions of Terzaghi’s one dimensional consolidation theory
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Q.11. A layer of saturated clay is 4m thick and is overlaid by 1m thick sand layer.
The clay has
Specific gravity = 2.7
Water content = 33% and
Compression index = 0.40.
The average overburden pressure in clay layer is 55 kN/m2. If the proposed
building on the clay deposit is going to increase the vertical pressure in
clay by 20kN/m2, estimate the probable final settlement of the building
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Q.12. Two clay layer A and B 5.6m thick in the field , the time taken by layer A
to reach 50% consolidation is 4 month, Calculate the time required for layer
B to reach the same degree of consolidation if layer A has double drainage
and layer b has single drainage. he coefficient of consolidation of layer b is
twice that of layer A.
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UNIT – VI
Q.1. Derive the relation between major and miner principal stresses
Q.2. Explain ‘Mohr’s circle method and prove that inclination of failure plane
in 45 + /2
Q.3. Write short note on (any three)
i) Tri-axial shear test
ii) Mohrs-Coulombs failure theory
iii) Sensitivity and thixotropy
iv) Unconfined compression test
Q.4. Describe direct shear strength test on soil sample with neat labeled
diagram.
Q.5. Explain the Mohr-Coulamb strength envelope
Q.6. What do you understand by the term stabilization of soil? Describe any
one method of soil stabilization.
Q.7. A specimen of clean dry cohesion less soil is tested in a shear box and
the soil is failed at a shear stress of 40kN/m2 when the normal load on
the specimen was 50 kN/m2. Determine:i)
The angle of shearing resistance.
ii)
The principal stresses during the failure.
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Q.8.
iii)
The direction of the principal planes.
A shear box test carried out on a soil sample gave:Test No.
1
2
3
Q.9.
Vertical stress(kN/m2)
100
200
300
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Horizon. shear stress (kN/m2)
80
144
216
Determine the magnitude of the major and minor principal stresses at
failure when the vertical stress on the sample was 200kM/m2.
Determine also the inclination to the horizontal of these stresses.
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A soil specimen when tasted in unconfined compression test fails at axial
test of 120kN/m2 the same sample tested in tri-axial compression test. The
failure occurs at cell pressure of 40kN/m2 and axial deviator stress of
160kN/m2. Determine shear strength parameter.
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