Civil Engineering PE Geotechnical Engineering and Slope Stability 3

Question 1

Terzaghi's ultimate bearing capacity equation for a strip footing is:

Accepted Answer

qu = cNc + qNq + 0.5γBNγ

Answer

For a strip footing, Terzaghi's equation is qu = cNc + qNq + 0.5γBNγ with shape factors of 1.0 for the strip geometry.

Question 2

Net allowable bearing capacity is calculated as:

Accepted Answer

(qu − q) / FS, where q is the overburden stress at footing depth

Answer

Net allowable bearing capacity = (qu − q)/FS, subtracting the existing overburden pressure before applying the safety factor.

Question 3

An SPT N-value of approximately 25 in clean sand most likely indicates:

Accepted Answer

Medium dense condition (Dr = 40–65%)

Answer

SPT N-values of roughly 10–30 in clean sand correspond to medium dense relative density per Gibbs and Holtz or Skempton correlations.

Question 4

Negative skin friction (downdrag) on a deep pile occurs when:

Accepted Answer

Surrounding consolidating soil settles more than the pile

Answer

Downdrag develops when settling soil moves downward relative to the pile shaft, imposing an additional downward drag force on the pile.

Question 5

The p-y method for laterally loaded piles models soil resistance as:

Accepted Answer

A series of nonlinear springs whose stiffness varies with depth and deflection

Answer

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.

Civil Engineering PE Practice Test

Civil Engineering PE Practice Test

Civil Engineering PE Geotechnical Engineering and Slope Stability 3