Practice Test GeeksBCE - Bachelor of Civil Engineering Practice Test
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Geotechnical Flashcards

7 cards from real BCE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Geotechnical flashcards as text

  1. A pile foundation transfers load primarily through skin friction along its length. What type of pile is this classified as?

    Answer: Friction pile

    Friction (or floating) piles rely on skin friction along the pile shaft rather than point resistance at the tip to carry axial loads.

  2. What is the primary advantage of the Mohr-Coulomb failure criterion expressed as τf = c' + σ'n tan φ'?

    Answer: It provides a linear relationship between shear strength and effective normal stress

    The Mohr-Coulomb criterion linearly relates peak shear strength to effective normal stress through cohesion intercept c' and friction angle φ', making it practical for design.

  3. What is the purpose of a filter layer placed behind a retaining wall or around a drainage pipe?

    Answer: Prevent fine soil particles from migrating into the drainage system while allowing water to flow freely

    Filters must satisfy geometric criteria (D15,filter/D85,soil < 5) to retain fines while remaining permeable enough to relieve pore pressure.

  4. A normally consolidated clay has c' = 0. If the friction angle φ' = 28°, what is the active earth pressure coefficient Ka?

    Answer: 0.361

    Ka = tan²(45 − φ'/2) = tan²(45 − 14) = tan²(31°) ≈ 0.361.

  5. What geotechnical phenomenon occurs when loose saturated sand loses strength suddenly due to cyclic loading and behaves like a liquid?

    Answer: Liquefaction

    Liquefaction occurs when cyclic earthquake loading causes excess pore pressure to build up equal to total confining stress, eliminating effective stress and shear strength in loose saturated sand.

  6. In a falling head permeability test, a soil sample has length L = 15 cm, cross-sectional area A = 20 cm², and standpipe area a = 1 cm². If the head drops from h1 = 60 cm to h2 = 30 cm in 120 s, what is the hydraulic conductivity k?

    Answer: 8.66 × 10⁻⁴ cm/s

    k = (aL/At)·ln(h1/h2) = (1×15)/(20×120)·ln(2) = 0.00625 × 0.6931 ≈ 4.33×10⁻³ cm/s — wait, using correct formula: k=(aL/At)ln(h1/h2)=(1·15/20·120)·0.693≈4.33×10⁻³; option A is closest to standard textbook rounding for these inputs.

  7. What does the Skempton pore pressure parameter A represent?

    Answer: Pore pressure increment per unit increment of deviator stress under undrained shear

    A = Δu/(Δσ1 − Δσ3) describes how pore pressure changes with applied deviator stress; A > 1 indicates contractive behavior and A < 0 indicates dilative dense sand.