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16-Civ-B3 Geotechnical Design: May 2017

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

  1. Question 1 Selecting site-investigation equipment for a silty deposit
  2. Question 2 Choice of triaxial or direct shear test for three field problems
  3. Question 3 Why field SPT values are corrected, and what governs a footing on dense sand
  4. Question 4 Why a steep excavation in clay stands unsupported for a short time
  5. Question 5 When the CPT is preferred to the SPT
  6. Question 6 Design axial capacity of a belled bored pile in layered clay
  7. Question 7 Terzaghi and general bearing-capacity equations with a moving water table
  8. Question 8 Anchored sheet pile wall by the free-earth-support method
  9. Question 9 Ultimate capacity of a pile group with negative skin friction

Start with Question 1 →

Paper format. National Examinations, May 2017 — 16-Civ-B3 Geotechnical Design; three hours, open book, any non-communicating calculator. Section A holds five discussion questions worth 7 marks each of which four are marked; Section B holds four design questions worth 24 marks each of which three are marked, so 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 marked script.

Reference texts. B. M. Das, Principles of Foundation Engineering, 7th–9th ed. (Cengage); B. M. Das, Principles of Geotechnical Engineering; R. F. Craig, Craig's Soil Mechanics, 8th ed. (Knappett & Craig); Canadian Geotechnical Society, Canadian Foundation Engineering Manual (CFEM), 4th ed.; J. E. Bowles, Foundation Analysis and Design; ASTM D1586 (SPT) and D5778 (CPT).

Source of charts and assumed values (page 1, Note 6). Every design coefficient used below is named where it is used: Terzaghi bearing-capacity factors from Das, Principles of Foundation Engineering, Table 3.1 (values computed by Kumbhojkar, 1993); Vesic/Reissner factors and the shape, depth and inclination factors from Das Table 3.4 and Eqs. (3.19)–(3.26); drilled-shaft adhesion factor alpha* = 0.55 from Reese & O'Neill (1989) as tabulated by Das, Chapter 12; bearing factor Nc* = 9 from Skempton (1951); earth-pressure coefficient for downdrag K' = 1 − sin(phi') from Das, Chapter 11; Janbu's bearing-capacity number for the pile point from Das Eq. (11.33). Assumed values (adhesion ratio, pile spacing, rigidity index) are stated in a callout beside the step that uses them.