Paper format. Professional Engineers Ontario /
Engineers Canada National Examinations, December 2015 — 98-Civ-B3 Geotechnical
Design. Three hours, OPEN BOOK, any non-communicating calculator. Section A carries five
discussion questions of 7 marks each (answer any four); Section B carries four design
questions of 24 marks each (answer any three); the examinable total is
4 × 7 + 3 × 24 = 100 marks. All nine questions are worked below, because
the set is a study resource rather than a timed attempt.
Reference texts (98-Civ-B3 / 16-Civ-B3 Geotechnical Design).
- B. M. Das, Principles of Foundation Engineering, 9th ed. — subsurface
exploration (Ch. 2), bearing capacity (Ch. 3), settlement of shallow foundations (Ch. 5),
stress increase in a soil mass (Ch. 6), retaining walls (Ch. 8), pile foundations
(Ch. 11).
- B. M. Das, Principles of Geotechnical Engineering, 9th ed. —
consolidation (Ch. 11), shear strength (Ch. 12), lateral earth pressure (Ch. 13), slope
stability (Ch. 15).
- Canadian Geotechnical Society, Canadian Foundation Engineering Manual
(CFEM), 4th ed. — the governing Canadian practice document for site investigation,
in-situ testing, bearing resistance, deep foundations, earth-retaining structures and
expansive soils.
- R. F. Craig, Craig's Soil Mechanics, 9th ed. — effective stress, earth
pressure theory and slope stability.
- D. P. Coduto, Foundation Design: Principles and Practices, 3rd ed. —
in-situ testing correlations and settlement of shallow foundations.
- M. J. Tomlinson & J. Woodward, Pile Design and Construction Practice,
6th ed. — shaft adhesion in clay, bored and augered piles, load testing.
Sources of design charts and assumed values (page-1 Note 6). Note 6 of
this paper requires the candidate to identify the source of every design chart used and
of every value assumed in the absence of data. They are named where used and collected
here:
- Q6 — Rankine active coefficient for a sloping backfill, Das,
Principles of Foundation Engineering, Eq. (8.5); base friction and adhesion
mobilisation factors $k_1 = k_2 = \tfrac{2}{3}$ after Das §8.5; Rankine passive
coefficient $K_p = \tan^2(45^{\circ} + \phi'_2/2)$. Assumed: stem height
$H = 10.0$ m (the exam omits it — see the callout in Q6); reinforced concrete
$\gamma_c = 24$ kN/m$^3$ (CFEM §4; CSA A23.3 normal-density concrete); the backfill
is fully drained so no water force acts.
- Q7 — overburden correction $C_N$ after Liao & Whitman
(1986); $\phi'$ from $(N_1)_{60}$ after Peck, Hanson & Thornburn (1974) as fitted by
Wolff (1989), cross-checked against Hatanaka & Uchida (1996); bearing capacity
factors from Das Table 3.3 (Prandtl–Reissner $N_q$, Vesic
$N_{\gamma} = 2(N_q+1)\tan\phi'$), shape factors after De Beer (1970) and depth factors
after Hansen (1970), Das Table 3.4; settlement from Meyerhof's (1965) SPT expression, Das
Eq. (5.42), cross-checked by Schmertmann's strain-influence method with
$E_s = 500(N_{60}+15)$ kPa. Assumed: founding depth $D_f = 2.0$ m; the sand is
uniform to at least $2B$ below the base; tolerable settlement 25 mm.
- Q8 — compression index from Terzaghi & Peck (1967),
$C_c = 0.009(LL-10)$; stress increase by the 2:1 method (Das §6.2) with a
Boussinesq rectangular-area cross-check (Das Table 6.6); Simpson weighting of
$\Delta\sigma'$ prescribed on the exam paper itself. Assumed:
$\gamma_w = 9.81$ kN/m$^3$; the clay is saturated so $e_0 = wG_s$; the sand layers are
incompressible relative to the clay.
- Q9 — undrained ($\phi_u = 0$) mass procedure, Das,
Principles of Geotechnical Engineering, §15.5; drained comparison by the
ordinary method of slices and Bishop's simplified method, Das §15.11–15.12,
and by the infinite-slope criterion, Das Eq. (15.10). Assumed: no external water
force and no seismic loading; the sliding mass is homogeneous.
Section A — discussion questions (7 marks each; answer any four)
