Geotechnical Engineering and Slope Stability Flashcards
6 cards from real Civil Engineering PE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Geotechnical Engineering and Slope Stability flashcards as text
Terzaghi's ultimate bearing capacity equation for a strip footing is:
Answer: qu = cNc + qNq + 0.5γBNγ
For a strip footing, Terzaghi's equation is qu = cNc + qNq + 0.5γBNγ with shape factors of 1.0 for the strip geometry.
Net allowable bearing capacity is calculated as:
Answer: (qu − q) / FS, where q is the overburden stress at footing depth
Net allowable bearing capacity = (qu − q)/FS, subtracting the existing overburden pressure before applying the safety factor.
An SPT N-value of approximately 25 in clean sand most likely indicates:
Answer: Medium dense condition (Dr = 40–65%)
SPT N-values of roughly 10–30 in clean sand correspond to medium dense relative density per Gibbs and Holtz or Skempton correlations.
Negative skin friction (downdrag) on a deep pile occurs when:
Answer: Surrounding consolidating soil settles more than the pile
Downdrag develops when settling soil moves downward relative to the pile shaft, imposing an additional downward drag force on the pile.
The p-y method for laterally loaded piles models soil resistance as:
Answer: A series of nonlinear springs whose stiffness varies with depth and deflection
Each p-y curve defines the nonlinear relationship between lateral soil resistance p and pile deflection y at a given depth, allowing analysis of nonlinear soil-pile interaction.
ASCE 7 seismic site classification (Site Classes A–F) is primarily determined by:
Answer: Average shear wave velocity in the upper 30 m (VS30)
ASCE 7 defines site classes using VS30, the time-averaged shear wave velocity over the top 30 meters; Site Class A/B = rock, E/F = soft soils.