Geotechnical · MCQ practice Shear Strength of Soils MCQs – Part 4
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Part 4 of 4 Question 46 Easy
The unconfined compressive strength test is a/an:
A Undrained test B Drained test C Consolidated undrained test D None of the above
Answer: A. Undrained test
The UCS test is quick and has no drainage — it is an undrained test (a special UU test with σ₃ = 0).
Question 47 Easy
The direct shear test suffers from the following disadvantage:
A Drainage conditions cannot be controlled B Pore water pressure cannot be measured C Shear stress on the failure plane is not uniform D All of the above
Answer: D. All of the above
All three are known disadvantages of the direct shear test.
Question 48 Easy
The triaxial test is usually carried out as:
A Unconsolidated undrained test B Consolidated undrained test C Undrained test D All of the above
Answer: D. All of the above
The triaxial apparatus can run UU, CU and CD tests; all the listed forms are standard.
Question 49 Medium
Due to a rise in the water table, the effective stress in soil:
A increases B decreases C does not change D may increase or decrease depending on the position of the water table
Answer: B. decreases
A rising water table within the soil increases pore pressure (and buoyancy), so effective stress decreases. (If the water table is already above ground, a further rise does not change it.)
Question 50 Easy
In a triaxial test, the intermediate principal stress is:
A Equal to zero B Equal to the confining pressure C Equal to the deviator stress D Equal to the deviator stress minus the confining stress
Answer: B. Equal to the confining pressure
In a triaxial compression test σ₂ = σ₃ = cell (confining) pressure.
Question 51 Easy
The actual movement of a soil mass is known as:
A Surface failure B Collapse C Slope failure D Base failure
Answer: C. Slope failure
Downward and outward movement of a soil mass along a slip surface is a slope failure.
Question 52 Medium
The total and effective stresses at a depth of 5 m below the top level of water in a pond are respectively:
A 0.0 and 0.0 B 0.5 kg/cm² and 0.0 C 0.5 kg/cm² and 0.6 kg/cm² D none of these
Answer: B. 0.5 kg/cm² and 0.0
σ = γw h = 10 × 5 = 50 kN/m² ≈ 0.5 kg/cm²; u = 0.5 kg/cm²; σ′ = 0.
Question 53 Easy
In a triaxial compression test on a soil specimen, the intermediate principal stress is equal to:
A major principal stress B minor principal stress C difference between major and minor principal stresses D none of these
Answer: B. minor principal stress
The two horizontal stresses are both the cell pressure, so σ₂ = σ₃ (the minor principal stress).
Part 4 of 4