Geotechnical Engineering QB
Geotechnical Engineering QB
Geotechnical Engineering QB
in JNTU World
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1. Group - A (Short Answer Questions)
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7 Explain quick sand condition Understand e
8 What are the salient characteristics of a flow net Remember e
UNIT – III
1 What is pressure bulb. Understand f
2 What are the expressions for the Boussinesq’s and westergaard’s Remember h
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solution for point load.
3 State Boussinesq’s equation for vertical stress at a point due to a load Evaluate h
on the surface of an elastic medium.
4 Derive the principle of construction of Newmark’s chart and explain Remember h
its use.
5 A load 1000KN acts as appoint load at the surface of the soil mass. Analyze h
Estimate the stress at a point 2m below 3m away from the point of
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action of the load by Boussinesq’s formula. Compare the value with
the result from Westergaard’s theory.
A circular area on the surface of an elastic mass of great extent
carries a uniformly distributed load of 120KN/m2. The radius of the
circle is 3m. compute the intensity of vertical pressure at a point 5m
Analyze h
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8 What are the factors effecting ofcohesionless soils. Understand i
9 What are the factors effecting of cohesive soils. Understand i
10 A series of direct shear test was conducted on soil each test was Analyze i
carried out till the same sample failed. The following results were
obtained. Determine cohesion intercept and angle of shearing
resistance
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Sample no Normal stress Shear stresses
2
(KN/m ) (KN/m2)
1 15 18
2 30 25
3 45 32
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Group - II (Long Answer Questions)
Questions
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Level
Program
Outcome
UNIT – I
2 Explain in detail the laboratory methods for grain size distribution of Remember a
fine and coarse soil.
3 Starting from three phase representation of soil mass, derive the Understand a
relationship between bulk unit weight, specific gravity, void ratio and
degree of saturation
4 With the help of three phase diagram, define the following: (i) Remember b
Voids ratio (ii) Porosity (iii) Degree of saturation (iv) Water content
(v) Absolute/true specific gravity (vi) Apparent specific gravity (vii)
Air content (viii) Percentage of air voids and (ix) Relative density.
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9 Discuss the importance of Atterberg’s limits of soil. Remember c
10 Discuss the method for determination of shrinkage limit of soil. Understand c
UNIT - II
1 Explain the factors affecting the permeability of soil. Understand d
2 Determination of coefficient of permeability in a laboratory and Understand d
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discuss their limitations.
3 What is darcy’slaw ?what are its limitations? Remember e
4 What are the characteristics of flow nets? Remember e
5 Discuss the properties and applications of flow nets and explain quick Understand e
sand phenomenon.
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6 Describe the electrical analogy of flow net construction. Remember e
7 Describe pumping-out method for the determination of the coefficient Understand d
of permeability in the field?
8 Describe pumping-in method for the determination of the coefficient Understand d
of permeability in the field?
9 Differentiate between absorbed and capillary water in soils and what Understand
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are the advantages and disadvantages of coefficient of permeability.
What is seepage velocity, coefficient of percolation and quick sand.
Remember
d
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5 How do you determine the pre-consolidation pressure and its Remember g
determination in soil engineering practice
6 Explain the significance of pre-consolidation pressure. Describe the Understand g
Casagrande method of determining it
7 Explain with spring analogy, Terzaghi’s theory of one dimensional Understand g
consolidation
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8 Write a brief procedure of consolidation test and to determine the Understand g
coefficient of consolidation by both logarithmic time fitting method
and square root of time method.
9 What is over consolidation soil? Explain briefly with an example. Remember g
10 Explain the square root of time fitting method of determining the Understand g
coefficient of consolidation of a clay sample.
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UNIT - V
1 Explain Mohr-Coulomb theory of shear strength. Sketch typical Remember i
strength envelope for a soft clay, clean sand and a silty clay
2 Classify the shear tests based on drainage conditions. Explain how the Understand i
pore pressure variation and volume change take place during these
tests. Enumerate the field conditions which necessitate each of these
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What types of field tests are necessary for determining the shear
strength parameters of sensitive clays?
What are the advantages and disadvantages of a triaxial compression
test in comparison with a direct shear test
Remember
Remember
i
5 What are the advantages and disadvantages of direct shear test over Remember i
triaxial test?
6 Explain about triaxial compression test Understand i
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7 Discuss the characteristics of cohesionless and cohesive soils. Understand i
8 Discuss modified failure envelope. What are its advantages and Remember i
disadvantages over the standard failure envelope.
9 Derive the relation between the principle stress at failure using mohr- Remember i
coulomb failure criterion.
10 Explain about liquefaction of soils. Understand i
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UNIT – I
1 A sample of saturated soil has a water content of 25% and a bulk unit Analyze a
weight of 20kN/m3 . Determine the (i) dry unit weight (ii) void ratio
(ii) specific gravity of the soil. What would be the bulk unit weight of
the soil if the soil is compacted for the same void ratio but with a
degree of saturation 90%.
2 A soil has a liquid limit and plastic limit of 47% and 33% Analyze c
respectively. If the volumetric shrinkage at the liquid limit and plastic
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limit are 44% and 29%. Determine the shrinkage limit.
3 An undisturbed sample of soil has a volume 100cm3 and mass 200g. Analyze b
on oven drying for 24 hours, the mass is reduced to 170g. If G= 2.68.
Determine the (i) void ratio (ii) water content and (iii) degree of
saturation of soil.
4 A cylindrical specimen of cohesive soil 10cm dia and 20cm length is Analyze b
prepared in a mould. If the wet weight is 2.25 kg and water content is
15%. Determine the dry unit weight and the void ratio. If G=2.7
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determine the degree of saturation of the sample.
5 A cylindrical specimen of cohesive soil 3.75cm dia and 7.5cm length Analyze b
weighing 175g. If the water content is 18% and G=2.68. Determine
the degree of saturation. What would be the error in the degree of
saturation , if it would have been an error of 1mm in measuring the
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length.
6 The plastic limit of soil is 25% and its plasticity index is 8%. When Analyze b
the soil is dried from its state at plastic limit, the volume change is
25% of its volume at plastic limit. Similarly the corresponding
volume change for the liquid limit to the dry state is 34% of its
volume at liquid limit. Determine the shrinkage limit and shrinkage
ratio.
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An undisturbed saturated specimen of clay has a volume of 18.9 cm3
and a mass of 30.2 g. On oven drying the mass reduces to 18 g. The
volume of dry specimen as determined by displacement of mercury is
9.9 cm2 . Determine the shrinkage limit, volumetric shrinkage,
specific gravity, shrinkage ratio.
A sample of sand above the water table was found to have a natural
Analyze
Analyze
c
b
moisture content of 15% and a unit weight of 18.84 kN/m3.
Laboratory tests on a dried sample indicated values of emin = 0.50
and emax = 0.85 for the densest and loosest states respectively.
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Compute the degree of saturation and the relative density. Assume Gs
= 2.65.
9 Earth is required to be excavated from borrow pits for building an Analyze b
embankment. The wet unit weight of undisturbed soil is 1 8 kN/m3
and its water content is 8%. In order to build a 4 m high embankment
with top width 2 m and side slopes 1:1, estimate the quantity of earth
required to be excavated per meter length of embankment. The dry
unit weight required in the embankment is 15 kN/m3 with a moisture
content of 10%. Assume the specific gravity of solids as 2.67. Also
determine the void ratios and the degree of saturation of the soil in
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test was 1 120 g, and Gs = 2.68. Determine (a) the hydraulic
conductivity in cm/sec, (b) the discharge velocity, and (c) the seepage
velocity
2 In a falling head permeameter, the sample used is 20 cm long having Analyze d
a cross-sectional area of 24 cm2. Calculate the time required for a
drop of head from 25 to 12 cm if the cross sectional area of the stand
pipe is 2 cm2. The sample of soil is made of three layers. The
thickness of the first layer from the top is 8 cm and has a value of k{
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= 2 x 10"4 cm/sec, the
second layer of thickness 8 cm has k2 = 5 x 10~4 cm/sec and the
bottom layer of thickness 4 cm has & k3 = 7 x 10-4 cm/sec. Assume
that the flow is taking place perpendicular to the layers
3 A sand sample of 0.25 m length was subjected to a constant head Analyze e
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permeability in a permeameter having an area of 307 x 10-4 m2. A
discharge of 100 cc was obtained in a period of 60 seconds under a
head of 0.39 m. Height of dry sand in the sample was 1350 grams
and the specific gravity of sand particles was 2.67. determine (i)
Coefficent of permeability (ii) Superficial velocity (iii) Seepage
velocity
4 In a falling head permability test, head causing flow was initially 500 Analyze d
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mm and it drops to 20 mm in 5 minutes. Calculate the time required
for the head to fall to 250 mm.
The following details refers to a test to determine the permeability of
the soil: Thickness of specimen =25 mm; diameter of specimen= 75
mm; diameter of standing pipe=10 mm; initial head at start=1000
mm; water level after 3hrs 20 minutes= 800 mm. Determine the
Analyze d
of top layer.
8 If a falling head permeameter test the initial head is 40 cm. The head Analyze d
drops by 5 cm in 10 minutes. Calculate the time required to run the
test for the final head to be 20 cm. If the sample is 6 cm in height and
50 cm2 in cross sectional area, calculate the coefficient of
permeability taking area of stand pipe = 0.5cm2 .
9 The water table in a certain area is at a depth of 4m below the ground Analyze e
surface. To a depth of 12m the soil consists of very fine sand having
an average void ratio of 0.65. Above the water table the sand has an
average degree of saturation of 50%. Calculate the effective pressure
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on a horizontal plane at a depth 10m below the earth surface
10 The water table in a deposit of sand 8m thick is at a depth of 3m Analyze e
below the surface. Above the water table the sand is saturated with
capillary water. The bulk density of sample is 19.62kN/m3 . Calculate
the effective pressure at 1m, 3m, 8m below the surface. Hence plot
the variation of total pressure, neutral pressure and effective pressure
at the depth of 8m.
UNIT-III
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1 A rectangular area of 2 m X 4m carries u.d.l. of 10t /m2 at the ground Analyze h
surface. Estimate the vertical pressure at the depth of 8m vertically
below a corner of the loaded area.
2 A circular area is loaded with a uniform load intensity of 100 kN/m2 Analyze h
at ground surface. Calculate the vertical pressure at a point P so
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situated on the vertical line through the centre of loaded area that the
area subtends an angle 90O at P. use the Boussinesq analysis.
3 Two column A and B are standing 5m apart. Load transferred through Analyze h
them may be taken as point load. Through column A a load of 400
kNare 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.
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A bed of compressible clay 4 m thick has pervious sand on the top
and impervious rock at the bottom. In a consolidation test on an
undisturbed sample of clay from this deposit, 90% settlement was
reached in 4 hours. The sample was 20 mm thick. Estimate the time
in years for the building founded over this deposit to reach 90% of its
settlement.
Analyze F
(i) Draw the compation curve (ii) Report the maximum dry unit
weight and optimum moisture content (iii) Draw 100% saturation line
7 Standard Proctor test conducted on a soil gave the following details: Analyze f
Bulk 18.0 19.0 19.6 20.5 21.0 20.5 20.1
density
(kN/m3)
Water 9.6 11.0 12.5 14.0 16.0 18.0 19.5
content (%)
Find OMC and maximum dry density by plotting compaction curve.
Determine degree of saturation at OMC, if G = 2.68
8 A soil has compression index of 0.28. At a stress of 120 kN/m2 the Analyze f
void ratio is 1.02. Compute (i) viod ratio if the stress on the soil is
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increased to 180 kN/m2 (ii) total settlement of the stratum of 6 m
thickness.
9 The maximum dry density of a sample by the light compaction test is Analyze f
1.78g/ml at an optimum water content of 15%. Find the air voids and
the degree of saturation. G =2.67 what would be the coreesponding
value of dry density on the zero air void line at O.W.C.
10 A cylindrical specimen of a cohesive soil of 10cm diameter and 20cm Analyze f
length was prepared by compaction in a mould. If the wet mass of the
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specimen wae 3.25Kg and its water content was 15% determine the
dry density and void ratio
If the specific gravity of the particles was 2.70 find the degree of
saturation.
UNIT-IV
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1 A soil sample 20 mm thick takes 20 minutes to reach 205 Analyze g
consolidation. Find the time taken for a clay layer 6 m thick to reach
40% consolidation. Assuming double drainage in both the cases.
2 The stresses on a failure plane in a drained test on a cohesionless soil Analyze g
are as under: Normal stress (σ) =100 kN/m2 Shear stress (τ) = 40
kN/m2 (i) Determine the angle of shearing resistance and the angle
which the failure plane makes with the major principal plane. Also
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find the major and minor principal stresses.
Saturated soil of 5 m thick lies above an impervious stratum and
below a pervious stratum. It has a compression index of 0.25 with
k = 3.2×10-10 m/sec. Its void ratio at a stress of 147 kN/m2 is 1.9.
Compute (i) The change in voids ratio due to increase of stress to 196
kN/m (ii) Coefficient of volume compressibility (iii) Coefficient of
Analyze g
deep and having 6%air content. Find also the void ratio and the dry
density of the specimen if G=2.68.
6 A long strip footing of width 2m carries a load of 400KN/m. calculate Analyze h
the maximum stress at a depth of 5m below the centre line of footing
compare the results with 2:1 distribution method.
7 Determine the vertical stress at a point p which is 3m below and at a Analyze h
radial distance of 3m from the vertical load of 100KN.Use
westergaard’s solution.
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8 A concentrated load of 1000KN acts vertically at the ground surface. Analyze h
Determine the vertical stress at a point which is at a) a depth of 2.5m
and a horizontal distance of 4.0m
b) at a depth of 5.0m and a radial distance of 2.5m
9 A square foundation of (5m x 5m) is to carry a load of Analyze h
4000KN.calculate the vertical stress at a depth of 5m below the centre
of the foundation. IN=0.084 for m=n=0.50
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a) also determine the vertical stress using the 1:2 distribution
10 Calculate the vertical stress at a point p at a depth of 2.5m directly Analyze h
under the centre of circular area of radius 2m and subjected to a load
100KN/m2. Also calculate the vertical stress at a point Q which is at
the same depth of 2.5m away from the centre of the loaded area.
UNIT –V
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1 A soil specimen when tasted in unconfined compression test fails at Analyze i
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.
2 A UU test is carried out on a saturated normally consolidated clay Analyze I
sample at a confining pressure of 3 kg/cm2. .The deviator stress at
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failure is 1 kg/cm2. W
Two samples were tested in a triaxialmachine.The all found pressure
maintained further first sample was 2kg/cm2 and 20kg/cm2 and the
failure occurred at additional axial stress of 7.7 kg/cm2,while for the
second the values were 5.0 kg/cm2 and 13.7 kg/m2 resp. Find c and ¢
Analyze i
of the soil.
4 A cylindrical specimen of a saturated soil fails at an axial stress of Analyze i
180 kN/m2 in an unconfined compression test. The failure plane
makes an angle of 54º with horizontal. Calculate the shear strength
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parameters of soil.
5 A remoulded specimen of soil prepared by compaction to standard Analyze i
proctor maximum dry unit weight at optimum moisture content, is
used for consolidated-undrainedtriaxial test with pore pressure
measurements. The test results are given below:
Test No Cell pressure Deviator stress at Pore pressure
kN/m2 failures kN/m2 kN/m2
1 40 300 05
2 100 443 10
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3 165 615 12
Determine the values of effective shear stress parameters by
(i) Drawing Mohr envelope (ii) Drawing modified envelope
6 A direct shear test was conducted on a soil, whose results are given Analyze i
below:
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deviator stress at failure when the cell pressure is 150 kN/m2
7 A vane 11.25 cm long, and 7.5 cm in diameter was pressed into soft Analyze i
clay at the bottom of a borehole. Torque was applied to cause failure
of soil. The shear strength of clay was found to be37 kN/m2.
Determine the torque that was applied.
8 A series of shear tests was performed on a soil. Each test was carried Analyze i
out until the soil sample sheared and the principal stress for each test
are as follows:
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Test σ3(KN/m2) σ1(KN/m2)
1 300 875
2 400 1160
3 500 1460
Plot the mohr circle of stress and determine strength envelope and
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angle of internal friction of the soil.
9 A direct shear test was performed on a 6cm x 6cm sample of dry sand Analyze i
the normal load was 360N. the failure occurred at a shear load of
180N.Plot the mohr strength envelope and determine ᴓ . Assume c=0
also determine principal stress at failure.
10 A series of direct shear test was conducted on soil each test was Analyze i
carried out till the same sample failed. The following results were
1
Sample no
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obtained. Determine cohesion intercept and angle of shearing
resistance and plot the mohr circle
15
Normal stress
(KN/m ) 2
20
Shear stresses
(KN/m2)
2 30 25
3 45 30
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