The 'residual shear strength' of over-consolidated clay is relevant for:
Choose the correct answer
Fresh compacted fill with no slip history
Existing (reactivated) slip surfaces in OC clay — platelet alignment gives lowest possible φ'r; must use residual for old landslides
Sand liquefaction analysis
Pile design in soft clay
Correct Answer
B. Existing (reactivated) slip surfaces in OC clay — platelet alignment gives lowest possible φ'r; must use residual for old landslides
Why is this the answer?
Residual strength: after large displacement (existing slip surface) φ'_r = much lower than peak φ'p; c'_r ≈ 0. Clay platelets align parallel to slip plane → very low friction. φ'_r = 8–15° for high-plasticity clays (bentonite); 20–25° for low-plasticity. Used in: stability analysis of first-time and reactivated landslides, old dam failures (sliding along pre-existing slip surface). Must be used if reactivation of old slip is possible.
Related Soil Mechanics MCQs
More solved Soil Mechanics questions for AE/JE Civil Engineering exams.
- The 'Hvorslev parameters' c_e and φ_e in soil mechanics refer to:
- The 'International Building Code' (IBC) and IS codes classify building sites for...
- 'Vibro-flotation' (vibro-compaction) is used to densify:
- The 'primary consolidation' of a clay layer settles because:
- The 'IS 2911' code series covers:
- The 'shear strength' of soil measured in an 'undrained triaxial test' (UU test) is:
Practice more Civil Engineering questions
This MCQ belongs to JE Level Premium Test Series. Full tests include timed attempts, rank comparison and subject-wise analysis.