Paper format: National Exams, December 2018 — 07-Str-B5 Foundation Engineering. Three hours, open book, any non-communicating calculator permitted. Six questions of equal value (30 marks each); five constitute a complete paper and only the first five appearing in the answer book are marked. All six are solved here. This subject is pure geotechnical engineering — the cover page names it Foundation Engineering.
Reference texts (the books an open-book candidate should have on the desk for this subject):
- Canadian Geotechnical Society, Canadian Foundation Engineering Manual (CFEM), 4th ed. — the Canadian limit-states framework, geotechnical resistance factors, frost depth, pile design.
- B. M. Das, Principles of Foundation Engineering, 9th ed. — bearing capacity with shape/depth/inclination factors, retaining walls, driven piles (§12), drilled shafts (§13), pile groups.
- R. F. Craig & J. Knappett, Craig's Soil Mechanics, 9th ed. — effective stress, Bishop's simplified method, consolidation settlement.
- M. J. Tomlinson & J. Woodward, Pile Design and Construction Practice, 6th ed. — adhesion factors, the equivalent-raft settlement method, block failure of pile groups.
- L. C. Reese & M. W. O'Neill, Drilled Shafts: Construction Procedures and Design Methods (FHWA) — the α* = 0.55 shaft rule and the exclusion zones used in Question 5.
- D. W. Taylor, Fundamentals of Soil Mechanics; A. W. Bishop & N. Morgenstern, Stability coefficients for earth slopes (Géotechnique, 1960) — the slope-stability charts behind Question 3.
Check — assumptions adopted across this paper. This examination omits at least one parameter that each design step needs. Every adoption is made explicitly here and flagged again at the point of use. (1) Questions 2 and 5 give no groundwater table. Both profiles are clays quoted by undrained shear strength, so they are saturated; the water table is therefore taken at ground level and effective stresses are computed with submerged unit weights. This is the conservative choice for settlement, and the sensitivity is reported in each answer (Question 2 settles 293 mm with the water table at surface against 153 mm with no free water). (2) Question 2 gives no adhesion factor. α is taken from Das's Table 12.6 (Terzaghi, Peck & Mesri, α against cu/pa) because that table needs no assumed effective-stress profile; the answer tabulates what Tomlinson's and the API's rules would give instead, and identifies the α at which the group size changes. (3) Question 1 does not say whether the quoted leg loads are factored. They are treated as specified (unfactored) loads, and both a serviceability check against the 200 kPa SLS capacity and an ultimate check at 1.4 × leg load against the 300 kPa factored resistance are carried out; the governing one is stated. (4) Question 5 gives no preconsolidation pressure. The requested Skempton correlation is used on the virgin compression line, and the (much smaller) settlement that follows if the profile's own cu/σ′v0 ratio of about 1.1 is honoured as an OCR of 2 is reported alongside. (5) Concrete unit weight is taken as 24 kN/m3 and γw as 9.81 kN/m3 throughout. (6) Where a question states only "factor of safety", the gross definition (ultimate bearing capacity over total applied pressure) is used, and the convention is restated in each answer.
