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16-Civ-B3 Geotechnical Design: May 2018

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

  1. Question 1 Equipment for the Reliable Determination of Settlement Behaviour in Sands
  2. Question 2 Factor of Safety for the Short-Term Stability of a Slope Excavated in Saturated Clay
  3. Question 3 Designing with Undrained Shear Strength — When, and How It Is Measured
  4. Question 4 Why a Steep Excavation in Clay Stands Unsupported for a Short Time
  5. Question 5 When to Prefer a Mat Foundation
  6. Question 6 Design Axial Capacity of a Belled Drilled Shaft in Clay
  7. Question 7 Corrected SPT Profile in a Sand Deposit
  8. Question 8 Factors of Safety of a Cantilever Retaining Wall against Overturning and Sliding
  9. Question 9 Schmertmann Settlement of a Continuous Footing on an Erratic Sand

Start with Question 1 →

Paper format. EGBC / Engineers Canada National Examination 16-Civ-B3 Geotechnical Design, May 2018. Three hours, open book, any non-communicating calculator. Section A — five discussion questions of 7 marks each, answer any four. Section B — four design questions of 24 marks each, answer any three. Examinable total $4\times 7 + 3\times 24 = 100$ marks. Page 1 Note 6 requires the candidate to identify clearly the source of every design chart and assumed value used, so the provenance of each correlation is named where it is used, not only in the concept notes. All nine questions are solved below, because the set is a study resource rather than a three-hour sitting.

Reference texts for this subject. B. M. Das, Principles of Foundation Engineering, 9th ed. (Cengage) — Ch. 3 (subsurface exploration and SPT corrections), Ch. 4 (bearing capacity), Ch. 5 (settlement, Schmertmann), Ch. 8 (retaining walls), Ch. 11–12 (pile foundations and drilled shafts); B. M. Das, Principles of Geotechnical Engineering, 9th ed. — Ch. 8 (shear strength), Ch. 15 (slope stability); R. D. Holtz, W. D. Kovacs & T. C. Sheahan, An Introduction to Geotechnical Engineering, 2nd ed.; Canadian Geotechnical Society, Canadian Foundation Engineering Manual (CFEM), 4th ed. — the Canadian design authority for the factors of safety and serviceability limits quoted here; L. C. Reese & M. W. O'Neill, Drilled Shafts: Construction Procedures and Design Methods (FHWA-HI-88-042).

Check — figure readings. Two dimensions are read from the drawings, as follows. (1) In Figure 2 the “1 m” dimension is the height of the bell: its arrows point inward at the flare, and scaling against the 4 m dimension on the same figure puts the bell base exactly on the 12 m line. The pile is therefore $L = 12$ m long with the bell top at 11 m, not 11 m long with its base floating 1 m clear of the layer base. (2) In Figure 3 the “0.35 m” label carries extension lines from the top and bottom corners of the base slab, so it is the base thickness; the “0.5 m” at the left is measured to the base underside, so only 0.15 m of soil covers the toe. The toe projection is not dimensioned and follows from the printed values as $4.0 - 0.3 - 2.0 = 1.7$ m. Figure 3 is not drawn to scale — its toe is drawn about half its dimensioned length — so the printed numbers govern, as page 1 Note 1 anticipates.