Engineers Canada Agricultural / Biosystems / Bioresource / Food Engineering examination syllabus · Canada · Provincial and territorial regulators (syllabus by Engineers Canada)
Original practice questions written to the published syllabus · not past papersSoil as an engineering material: its phases, flow of water through it, compaction, consolidation, shear strength and stability.
In the exams: GATE AG Section 4 (soil mechanics asked in 6 of 8 papers 2019–26); ICAR AIEEA-PG Unit IV; NCEES PE soils and foundations
How our questions for Engineers Canada Agricultural / Biosystems / Bioresource / Food Engineering examination syllabus spread across the units of Soil Mechanics. Difficulty: 13 easy, 11 medium, 2 hard.
| Index properties and soil classification | 6 | |
| Phase relations | 4 | |
| Permeability | 4 | |
| Effective stress | 4 | |
| Shear strength and the Mohr-Coulomb criterion | 3 | |
| Compaction and the Proctor test | 2 | |
| Terzaghi one-dimensional consolidation | 1 | |
| Earth pressure: active and passive (Rankine) | 1 | |
| Bearing capacity basics | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
In a hydrometer analysis, how long does a spherical particle of diameter 0.01 mm and specific gravity 2.65 take to settle 100 mm in water of viscosity 1.0 × 10⁻³ Pa·s (γw = 9.81 kN/m³)?
B. 18.5 min
Stokes' law: v = (γs − γw)D²/(18μ) = (2.65 − 1) × 9810 × (1.0 × 10⁻⁵)²/(18 × 10⁻³) = 8.993e-05 m/s. Time = 0.1/v = 1112 s = 18.5 min. Using γs instead of (γs − γw) ignores buoyancy and gives 11.5 min; the other options are factor-of-ten unit slips.
Further reading: Das and Sobhan, Principles of Geotechnical Engineering
In a falling-head test, the standpipe area is 1.0 cm², the specimen is 10 cm long with an area of 50 cm², and the head falls from 100 cm to 50 cm in 600 s. What is k?
D. 2.31e-04 cm/s
k = (aL/(At))·ln(h1/h2) = (1.0 × 10)/(50 × 600) × ln 2 = 3.333e-04 × 0.693 = 2.31e-04 cm/s. Using log10 without the 2.303 factor gives 1.00e-04; swapping the standpipe and specimen areas gives an absurdly high 5.78e-01.
Further reading: Das and Sobhan, Principles of Geotechnical Engineering
A sand deposit has a water table 3 m below ground. Above it the sand's unit weight is 17 kN/m³; below it the saturated unit weight is 19.5 kN/m³. With γw = 9.81 kN/m³, what is the vertical effective stress at 8 m depth?
D. 99.45 kPa
σ = 17 × 3 + 19.5 × 5 = 148.5 kPa. u = 9.81 × 5 = 49.05 kPa (water depth is 5 m, not 8 m). σ′ = 99.45 kPa. Measuring u from the ground surface gives 70.02; using γsat above the water table gives 106.95.
Further reading: Das and Sobhan, Principles of Geotechnical Engineering
If the compactive effort applied to a soil is increased, how do its maximum dry density and optimum moisture content change?
D. Maximum dry density rises; optimum moisture content falls
More energy packs the grains more closely with less water needed for lubrication, so the curve moves up and to the left. This is why the modified Proctor test gives a higher maximum dry density at a lower optimum than the standard test.
Further reading: Das and Sobhan, Principles of Geotechnical Engineering
Which assumption underlies Rankine's earth pressure theory?
D. The back of the wall is vertical and perfectly smooth
Rankine assumed a smooth vertical wall so that the stresses in a semi-infinite soil mass in plastic equilibrium apply directly. Wall friction is included in Coulomb's wedge theory; the log-spiral surface is used in more refined passive calculations.
Further reading: Das and Sobhan, Principles of Geotechnical Engineering
How does compaction differ from consolidation?
D. Compaction expels air quickly by mechanical energy; consolidation slowly expels water from saturated soil under sustained load
Compaction is a rapid densification of partly saturated soil by rolling, tamping or vibration that reduces air voids. Consolidation is the gradual volume decrease of a saturated soil as pore water drains under a sustained load, governed by permeability.
Further reading: Das and Sobhan, Principles of Geotechnical Engineering
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