Soil Shear Strength and Stress Distribution - Geotechnical Engineering - Civil Engineering Previous Year Questions

1

2014 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2014 [Session 1]

For a saturated cohesive soil, a triaxial test yields the angle of internal friction (\( \phi \)) as zero. The conducted test is

A

Consolidated Drained (CD) test

B

Consolidated Undrained (CU) test

C

Unconfined Compression (UC) test

D

Unconsolidated Undrained (UU) test

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2

2015 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2015 [Session 2]

Stress path equation for tri-axial test upon application of deviatoric stress is, q = 10√3 + 0.5 p. The respective values of cohesion, c (in kPa) and angle of internal friction, φ are:

A

20 and 20°

B

20 and 30°

C

30 and 30°

D

30 and 20°

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3

2016 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2016 [Session 1]

A drained triaxial compression test on a saturated clay yielded the effective shear strength parameters as \(c' = 15\) kPa and \(\phi' = 22°\). Consolidated Undrained triaxial test on an identical sample of this clay at a cell pressure of 200 kPa developed a pore water pressure of 150 kPa at failure. The deviator stress (expressed in kPa) at failure is __________

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4

2017 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2017 [Session 2]

Consider the following statements related to the pore pressure parameters, \(A\) and \(B\):
P. \(A\) always lies between 0 and 1.0
Q. \(A\) can be less than 0 or greater than 1.0
R. \(B\) always lies between 0 and 1.0
S. \(B\) can be less than 0 or greater than 1.0
For these statements, which one of the following options is correct?

A

P and R

B

P and S

C

Q and R

D

Q and S

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5

2017 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2017 [Session 2]

Following are the statements related to the stress paths in a triaxial testing of soils:
P. If \(\sigma_1 = \sigma_3\), the stress point lies at the origin of the \(p-q\) plot.
Q. If \(\sigma_1 = \sigma_3\), the stress point lies on the \(p\)-axis of the \(p-q\) plot.
R. If \(\sigma_1 > \sigma_3\), both the stress points \(p\) and \(q\) are positive.
For the above statements, the correct combination is

A

P – False; Q – True; R – True

B

P – True; Q – False; R – True

C

P – False; Q – True; R – False

D

P – True; Q – False; R – False

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6

2017 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2017 [Session 2]

Consider a square-shaped area ABCD on the ground with its centre at M as shown in the figure. Four concentrated vertical loads of P = 5000 kN are applied on this area, one at each corner.

The vertical stress increment (in kPa, up to one decimal place) due to these loads according to the Boussinesq’s equation, at a point 5 m right below M, is __________

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7

2018 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2018 [Session 2]

The total horizontal and vertical stresses at a point X in a saturated sandy medium are 170 kPa and 300 kPa, respectively. The static pore-water pressure is 30 kPa. At failure, the excess pore-water pressure is measured to be 94.50 kPa, and the shear stresses on the vertical and horizontal planes passing through the point X are zero. Effective cohesion is 0 kPa and effective angle of internal friction is 36°. The shear strength (in kPa, up to two decimal places) at point X is ______

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8

2019 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2019 [Session 2]

A 2 m × 4 m rectangular footing has to carry a uniformly distributed load of 120 kPa. As per the 2:1 dispersion method of stress distribution, the increment in vertical stress (in kPa) at a depth of 2 m below the footing is ____________

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9

2022 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2022 [Session 2]

Stresses acting on an infinitesimal soil element are shown in the figure (with \(\sigma_z > \sigma_x\)). The major and minor principal stresses are \(\sigma_1\) and \(\sigma_3\), respectively. Considering the compressive stresses as positive, which one of the following expressions correctly represents the angle between the major principal stress plane and the horizontal plane?

A

\(\tan^{-1} \left( \frac{\tau_{zx}}{\sigma_1 - \sigma_r} \right)\)

B

\(\tan^{-1} \left( \frac{\tau_{zx}}{\sigma_x - \sigma_r} \right)\)

C

\(\tan^{-1} \left( \frac{\tau_{zx}}{\sigma_1 + \sigma_x} \right)\)

D

\(\tan^{-1} \left( \frac{\tau_{zx}}{\sigma_1 + \sigma_3} \right)\)

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10

2022 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2022 [Session 2]

A concentrically loaded isolated square footing of size 2 m × 2 m carries a concentrated vertical load of 1000 kN. Considering Boussinesq’s theory of stress distribution, the maximum depth (in m) of the pressure bulb corresponding to 10 % of the vertical load intensity will be _____. (round off to two decimal places)

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11

2022 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2022 [Session 2]

In a triaxial unconsolidated undrained (UU) test on a saturated clay sample, the cell pressure was 100 kPa. If the deviatoric stress at failure was 150 kPa, then the undrained shear strength of the soil is _____ kPa. (in integer)

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12

2022 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2022 [Session 2]

Match the following in Column X with Column Y:

Column X	Column Y
(P) In a triaxial compression test, with increase of axial strain in loose sand under drained shear condition, the volumetric strain	(I) decreases.
(Q) In a triaxial compression test, with increase of axial strain in loose sand under undrained shear condition, the excess pore water pressure	(II) increases.
(R) In a triaxial compression test, the pore pressure parameter "B" for a saturated soil	(III) remains same.
(S) For shallow strip footing in pure saturated clay, Terzaghi's bearing capacity factor \(N_q\) due to surcharge	(IV) is always 0.0.

Which one of the following combinations is correct?

A

(P)-(I), (Q)-(II), (R)-(V), (S)-(V)

B

(P)-(II), (Q)-(I), (R)-(IV), (S)-(V)

C

(P)-(I), (Q)-(III), (R)-(VI), (S)-(IV)

D

(P)-(I), (Q)-(II), (R)-(V), (S)-(VI)

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13

2024 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2024 [Session 2]

Which one of the following saturated fine-grained soils can attain a negative Skempton's pore pressure coefficient (A)?

A

Quick clays

B

Normally-consolidated clays

C

Lightly-consolidated clays

D

Over-consolidated clays

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14

2024 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2024 [Session 2]

A drained triaxial test was conducted on a saturated sand specimen using a stress-path triaxial testing system. The specimen failed when the axial stress reached a value of 100 kN/m² from an initial confining pressure of 300 kN/m².
The angle of shearing plane (in degrees) with respect to horizontal is __________
(rounded off to the nearest integer).

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15

2025 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2025 [Session 1]

The results of a consolidated drained triaxial test on a normally consolidated clay are shown in the figure. The angle of internal friction is

A

\(\sin^{-1}\left(\frac{1}{2}\right)\)

B

\(\sin^{-1}\left(\frac{1}{3}\right)\)

C

\(\sin^{-1}\left(\frac{2}{3}\right)\)

D

\(\sin^{-1}\left(\frac{3}{4}\right)\)

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16

2025 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2025 [Session 1]

A cut slope is made in a silty clay soil for a new road project, as shown in the figure. The locations of ground water table (GWT) and potential failure surface are shown in the figure. After the cut is made, the excess pore water pressure is fully dissipated, and the shear stress at the point A is 60 kN/m². The factor of safety at the point A for long-term stability is __________ (rounded off to 2 decimal places). Note: Shear strength properties of silty clay: c' = 15 kN/m², φ' = 15°, and c_u = 75 kN/m² Unit weight of soil above the GWT (γ) = 19 kN/m³ Unit weight of soil below the GWT (γ_sat) = 20 kN/m³ Unit weight of water (γ_w) = 9.81 kN/m³

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17

2025 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2025 [Session 2]

In the context of shear strength of soil, which of the following statements is/are CORRECT?

A

The unconfined compression test is a special case of the unconsolidated-undrained (UU) triaxial tests.

B

The shear strength parameters obtained from the consolidated-drained (CD) triaxial tests should be used to analyse rapid construction in clay.

C

Vane shear test is commonly used for determining in situ undrained strength of saturated clay soils.

D

In an unconsolidated-undrained (UU) triaxial tests, the angle of internal friction (\(\phi\)) is equal to zero.

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18

2008 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2008

A footing 2 m × 1 m exerts a uniform pressure of 150 kN/m² on the soil. Assuming a load dispersion of 2 vertical to 1 horizontal, the average vertical stress (kN/m²) at 1.0 m below the footing is

A

50

B

75

C

80

D

100

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19

2008 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2008

A direct shear test was conducted on a cohesionless soil (c = 0) specimen under a normal stress of 200 kN/m². The specimen failed at a shear stress of 100 kN/m². The angle of internal friction of the soil (degrees) is

A

26.6

B

29.5

C

30.0

D

32.6

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20

2010 · Civil Engineering · Geotechnical Engineering · Soil Shear Strength and Stress Distribution

Civil Engineering (CE) 2010

The vertical stress at point \( P_1 \) due to the point load Q on the ground surface as shown in figure is \( \sigma_z \). According to Boussinesq’s equation, the vertical stress at point \( P_2 \) shown in figure will be

A

\(\sigma_z / 2 \)

B

\(\sigma_z \)

C

\(2\sigma_z \)

D

\(4\sigma_z \)

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