National Exams — May 2015 — 04-Geol-06, Soil Mechanics. Three-hour, closed-book exam; one of two approved calculators permitted, plus a compass and ruler. Candidates must answer Questions 1 to 5 and choose three of the five sub-questions in Question 6 (5 marks each); all five Question-6 parts are answered here as a complete study resource.
Reference texts: Das, Principles of Geotechnical Engineering — USCS classification (Q1), phase relations (Q2), consolidation theory (Q4), Boussinesq/Newmark stress-influence factors (Q4), flow nets and seepage (Q5), sand-cone compaction (Q6d); Craig, Craig's Soil Mechanics — Mohr-circle shear strength and limit-equilibrium slope stability (Q3), effective stress and capillarity (Q6b, Q6c); EGBC Geoscience Professional Practice Guidelines for assumption-disclosure conventions.
Check — reading notes. (1) Table Q1's percent-finer values are read as 99% and 98%; the sieve-size row labels "420 μm", "150 μm", "75 μm" are the No. 40, No. 100 and No. 200 sieves. (2) Figure Q5's flow net (equipotential/flow-line count, and the relative positions of points A–D on specific equipotentials) was read from the exam's printed figure — Nf=3 flow channels and Nd=8 equipotential drops, with A on drop 1, point 1 on drop 2, point 2/B on drop 3, point 3 on drop 4, point 4/C on drop 5, point 5 on drop 6, D on drop 7, and the downstream boundary at drop 8; this is a reading of the figure rather than printed exam text. (3) The elevation-head datum for Q5.2 is taken at the impervious layer (z=0), so the ground surface/dam base sits at z=H=10 m and the headwater surface at z=H+ht=20 m — this datum choice is the one that makes the given zA,zB,zC,zD values produce physically valid (positive) pore pressures at all four points, and is disclosed since the exam figure is schematic, not to scale. (4) Q4's Boussinesq corner-influence factors were computed directly from Newmark's closed-form integral rather than read from the exam's Table 8B.
