NCEES Geotechnical Engineering 2 — Questions and Answers
Question 1: For the NCEES PE Geotechnical exam, the factor of safety against slope failure using the ordinary method of slices is:
- FS = Sum of resisting moments / Sum of driving moments (Correct answer)
- FS = Total active force / Total passive force
- FS = Net bearing capacity / Applied load
- FS = Cv / time factor
Correct answer: FS = Sum of resisting moments / Sum of driving moments
The ordinary (Fellenius) method computes FS as the ratio of sum of resisting moments to sum of driving moments about the slip circle center.
Question 2: In NCEES PE Geotechnical engineering, the liquefaction susceptibility of saturated sands is most influenced by:
- Plasticity index and liquid limit
- Relative density, grain size, and cyclic shear stress ratio (Correct answer)
- Overconsolidation ratio of clay layers
- Coefficient of permeability
Correct answer: Relative density, grain size, and cyclic shear stress ratio
Liquefaction susceptibility depends primarily on relative density (or N-value), uniformly graded fine sand, and the cyclic stress ratio from earthquake loading.
Question 3: On the NCEES PE Geotechnical exam, the immediate (elastic) settlement of a foundation differs from consolidation settlement in that it:
- Occurs only in granular soils and is time-independent (Correct answer)
- Occurs in clays during primary consolidation over years
- Is irreversible permanent deformation
- Only occurs under dynamic loading
Correct answer: Occurs only in granular soils and is time-independent
Immediate (elastic) settlement occurs rapidly upon load application, primarily in granular soils, and is calculated using elasticity theory.
Question 4: In NCEES PE Geotechnical practice, the purpose of a geosynthetic geogrid in pavement design is to:
- Waterproof the subgrade layer
- Reinforce and stabilize the base course by providing lateral confinement (Correct answer)
- Drain subsurface water from the roadway base
- Separate fine-grained subgrade from coarse aggregate
Correct answer: Reinforce and stabilize the base course by providing lateral confinement
Geogrids provide lateral confinement and reinforcement to aggregate base layers, increasing load distribution and reducing rutting.
Question 5: For the NCEES PE Geotechnical exam, the end-bearing capacity of a driven pile in clay is estimated using:
- α-method (adhesion factor) applied to pile tip area
- Qp = 9Su × Ap, where Su is undrained shear strength (Correct answer)
- Meyerhof bearing capacity factors for deep foundations
- SPT N-value times 8 kip/ft²
Correct answer: Qp = 9Su × Ap, where Su is undrained shear strength
End bearing in clay: Qp = 9Su × Ap, using the bearing capacity factor Nc = 9 for deep foundations in undrained clay.
Question 6: In NCEES PE Geotechnical engineering, Darcy's Law for seepage through soil states that seepage velocity v equals:
- v = n × Ki (porosity times hydraulic conductivity times gradient)
- v = Ki (hydraulic conductivity times hydraulic gradient) (Correct answer)
- v = K/i (conductivity divided by gradient)
- v = γw × i/K
Correct answer: v = Ki (hydraulic conductivity times hydraulic gradient)
Darcy's seepage velocity v = Ki, where K is hydraulic conductivity and i is the hydraulic gradient.
NCEES Geotechnical Engineering 2
For the NCEES PE Geotechnical exam, the factor of safety against slope failure using the ordinary method of slices is: