Soils Level IV Practice Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026/2027 Q&A |
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1. A senior soils technician is reviewing a laboratory’s triaxial
compression test results. Which parameter is most critical for
evaluating long-term slope stability under drained conditions?
A. Undrained shear strength (Su)
B. Pore water pressure at failure
C. Effective friction angle (φ′)
D. Unconfined compressive strength
Answer: C
Effective stress parameters, particularly the effective friction angle,
govern long-term drained behavior and slope stability.
2. When overseeing a geotechnical investigation, which condition most
strongly justifies the use of consolidated drained (CD) triaxial tests?
, A. Rapid loading conditions
B. Saturated clay with short-term loading
C. Granular soil with long-term loading
D. Soil with high plasticity index
Answer: C
CD tests simulate long-term conditions where pore pressures
dissipate, typical for granular soils.
3. In reviewing a compaction control program, which factor has the
greatest influence on maximum dry density?
A. Number of roller passes
B. Lift thickness
C. Compactive effort
D. Field moisture variation
Answer: C
Maximum dry density is fundamentally a function of the applied
compactive energy.
4. A discrepancy is found between laboratory Proctor results and field
density tests. Which action should a Level IV technician recommend
first?
A. Reject all field work
B. Increase field compaction effort
C. Verify that laboratory and field moisture contents are comparable
D. Change the specified density requirement
, Answer: C
Differences in moisture content often explain density discrepancies
and should be checked before corrective action.
5. Which soil property primarily controls consolidation settlement
magnitude?
A. Shear strength
B. Permeability
C. Compression index (Cc)
D. Plastic limit
Answer: C
Compression index quantifies soil compressibility and directly affects
settlement magnitude.
6. In a one-dimensional consolidation test, which curve is used to
estimate preconsolidation pressure?
A. Time–settlement curve
B. Void ratio–log pressure curve
C. Stress–strain curve
D. Degree of saturation curve
Answer: B
Preconsolidation pressure is determined from the void ratio versus
log effective stress plot.
7. Which factor most affects the rate of consolidation in fine-grained
soils?
, A. Compression index
B. Plasticity index
C. Coefficient of consolidation (Cv)
D. Unit weight
Answer: C
Cv governs how quickly pore water pressure dissipates during
consolidation.
8. When reviewing Atterberg limits data, a high plasticity index generally
indicates:
A. Low compressibility
B. High permeability
C. High shrink–swell potential
D. Low cohesion
Answer: C
High PI soils are typically more compressible and susceptible to
volume change.
9. Which test result is most useful for classifying coarse-grained soils
under USCS?
A. Liquid limit
B. Plastic limit
C. Grain size distribution
D. Specific gravity