Civil Engineering PE Shallow and Deep Foundations 4

Question 1

A 2.5-ft wide strip footing is founded 3 ft below grade in clay with Su = 800 psf. Using Hansen's bearing capacity factors (Nc = 5.14, sc = 1.0 for strip), the gross ultimate bearing capacity is approximately:

Accepted Answer

4,112 psf + overburden

Answer

q_ult = Su × Nc = 800 × 5.14 = 4,112 psf (net), plus the overburden pressure γDf = 120 × 3 = 360 psf for gross capacity.

Question 2

The wave equation analysis (WEAP) for driven piles is used primarily to:

Accepted Answer

Predict driving resistance and evaluate hammer-pile-soil system performance during installation

Answer

WEAP models stress wave propagation to predict blow counts at refusal, check driving stresses, and confirm pile capacity during installation.

Question 3

For a rectangular footing with dimensions B × L, the Meyerhof shape factor for the cohesion term (sc) is:

Accepted Answer

1 + 0.2(B/L)Kp

Answer

Meyerhof's shape factor for cohesion is sc = 1 + 0.2(B/L)Kp, where Kp = tan²(45 + φ/2).

Question 4

An H-pile driven to rock refusal develops its load primarily through:

Accepted Answer

End bearing at the pile tip with minimal skin friction contribution

Answer

H-piles driven to rock refusal rely almost entirely on end bearing since the relatively small tip area concentrates stress at the rock surface.

Question 5

The Davisson offset limit method for determining pile capacity from a static load test uses an offset of:

Accepted Answer

0.15 in + pile diameter/120

Answer

Davisson's criterion defines failure at a settlement equal to the elastic compression of the pile plus an offset of 0.15 in + D/120 (where D is diameter in inches).

Civil Engineering PE Practice Test

Civil Engineering PE Practice Test

Civil Engineering PE Shallow and Deep Foundations 4