Alabama Retaining Wall Contractor
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the primary purpose of a retaining wall?
A. To increase roof drainage
B. To support and retain soil at different elevations
C. To replace a building foundation
D. To prevent concrete curing
Answer: B. To support and retain soil at different elevations
Rationale: Retaining walls are designed to resist lateral earth pressure and
hold soil in place where there is a difference in ground elevation.
2. Which soil condition generally creates the greatest concern for
retaining-wall stability?
,A. Well-drained granular soil
B. Dry, compacted sand
C. Saturated soil with poor drainage
D. Uniform gravel
Answer: C. Saturated soil with poor drainage
Rationale: Water increases lateral pressure and may create hydrostatic
pressure behind the wall, reducing stability and increasing the risk of
failure.
3. What is hydrostatic pressure?
A. Pressure caused by wind
B. Pressure exerted by standing or trapped water
C. Pressure caused by concrete shrinkage
D. Pressure caused by sunlight
Answer: B. Pressure exerted by standing or trapped water
Rationale: Hydrostatic pressure develops when water accumulates behind
a retaining wall and is not properly drained.
4. Which component is commonly installed behind a retaining wall to
promote drainage?
,A. Expansive clay
B. Drainage aggregate
C. Topsoil
D. Untreated wood chips
Answer: B. Drainage aggregate
Rationale: Clean, free-draining aggregate allows water to move toward
drainage outlets and reduces hydrostatic pressure.
5. What is the principal function of a perforated foundation drain behind
a retaining wall?
A. To increase soil pressure
B. To collect and convey groundwater away from the wall
C. To strengthen the concrete
D. To support wall reinforcement
Answer: B. To collect and convey groundwater away from the wall
Rationale: A perforated drain collects water from the drainage zone and
directs it to a suitable outlet.
6. Which retaining-wall failure involves the entire wall moving forward
along its base?
, A. Overturning
B. Sliding
C. Settlement
D. Spalling
Answer: B. Sliding
Rationale: Sliding occurs when lateral forces exceed the resistance
provided by base friction, soil resistance, and other stabilizing measures.
7. Which failure mode occurs when a retaining wall rotates forward
about its toe?
A. Sliding
B. Overturning
C. Corrosion
D. Shrinkage
Answer: B. Overturning
Rationale: Overturning occurs when lateral earth pressure creates a
moment greater than the resisting moment provided by the wall’s weight
and geometry.
8. What is the “toe” of a retaining-wall footing?
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a retaining wall?
A. To increase roof drainage
B. To support and retain soil at different elevations
C. To replace a building foundation
D. To prevent concrete curing
Answer: B. To support and retain soil at different elevations
Rationale: Retaining walls are designed to resist lateral earth pressure and
hold soil in place where there is a difference in ground elevation.
2. Which soil condition generally creates the greatest concern for
retaining-wall stability?
,A. Well-drained granular soil
B. Dry, compacted sand
C. Saturated soil with poor drainage
D. Uniform gravel
Answer: C. Saturated soil with poor drainage
Rationale: Water increases lateral pressure and may create hydrostatic
pressure behind the wall, reducing stability and increasing the risk of
failure.
3. What is hydrostatic pressure?
A. Pressure caused by wind
B. Pressure exerted by standing or trapped water
C. Pressure caused by concrete shrinkage
D. Pressure caused by sunlight
Answer: B. Pressure exerted by standing or trapped water
Rationale: Hydrostatic pressure develops when water accumulates behind
a retaining wall and is not properly drained.
4. Which component is commonly installed behind a retaining wall to
promote drainage?
,A. Expansive clay
B. Drainage aggregate
C. Topsoil
D. Untreated wood chips
Answer: B. Drainage aggregate
Rationale: Clean, free-draining aggregate allows water to move toward
drainage outlets and reduces hydrostatic pressure.
5. What is the principal function of a perforated foundation drain behind
a retaining wall?
A. To increase soil pressure
B. To collect and convey groundwater away from the wall
C. To strengthen the concrete
D. To support wall reinforcement
Answer: B. To collect and convey groundwater away from the wall
Rationale: A perforated drain collects water from the drainage zone and
directs it to a suitable outlet.
6. Which retaining-wall failure involves the entire wall moving forward
along its base?
, A. Overturning
B. Sliding
C. Settlement
D. Spalling
Answer: B. Sliding
Rationale: Sliding occurs when lateral forces exceed the resistance
provided by base friction, soil resistance, and other stabilizing measures.
7. Which failure mode occurs when a retaining wall rotates forward
about its toe?
A. Sliding
B. Overturning
C. Corrosion
D. Shrinkage
Answer: B. Overturning
Rationale: Overturning occurs when lateral earth pressure creates a
moment greater than the resisting moment provided by the wall’s weight
and geometry.
8. What is the “toe” of a retaining-wall footing?
