Civil Engineering PE Shallow and Deep Foundations 3

Question 1

A 16-in diameter closed-end steel pipe pile is driven 40 ft into medium-dense sand (φ = 32°, γ = 115 pcf).
Using the β method with β = 0.30, what is the total unit skin friction at a depth of 20 ft?

Accepted Answer

690 psf

Answer

575 psf

Answer

460 psf

Answer

805 psf

Question 2

Punching shear failure in a shallow foundation is most likely when:

Accepted Answer

The foundation is on loose sand or soft clay and the depth-to-width ratio is small

Answer

The foundation is on dense gravel with high confinement

Answer

The footing is very wide relative to its depth

Answer

The footing is loaded by eccentric moments only

Question 3

A pile group efficiency factor less than 1.0 indicates that:

Accepted Answer

The group capacity is less than the sum of individual pile capacities due to overlapping stress zones

Answer

Each pile in the group carries more load than a single isolated pile

Answer

The piles are too closely spaced for driving equipment

Answer

The pile cap reduces lateral capacity

Question 4

Which of the following parameters is NOT directly used in Skempton's bearing capacity equation for saturated clay (φ = 0)?

Accepted Answer

Angle of internal friction φ

Answer

Undrained shear strength Su

Answer

Shape factor sc

Answer

Depth factor dc

Question 5

The primary purpose of a pile load test (ASTM D1143) is to:

Accepted Answer

Verify pile capacity and measure load-settlement behavior at the specific site

Answer

Determine soil stratification and SPT N-values

Answer

Measure pile installation energy during driving

Answer

Evaluate corrosion potential of the pile material

Question 6

Heave failure at the bottom of a deep excavation in soft clay is evaluated using the factor of safety against:

Accepted Answer

Basal heave, using Terzaghi's or Bjerrum-Eide's method with Su and excavation geometry

Answer

Slope stability with Bishop's circular arc method

Answer

Bearing capacity with surcharge correction

Answer

Consolidation settlement with Cv and drainage path

Question 7

According to ASCE 7, the minimum depth of a foundation in frost-susceptible soils must be:

Accepted Answer

Below the local frost depth as established by the local building code or authority

Answer

At least 12 inches below finished grade

Answer

A minimum of 3 ft regardless of climate

Answer

Below the seasonal groundwater table