What is the coefficient K₀ for at-rest earth pressure when φ' = 30°?

K₀ = 1 - sin(30°) = 1 - 0.5 = 0.5

True or False: Active earth pressure develops when a wall moves toward the soil.

False. Active pressure develops when the wall moves away from soil, allowing lateral expansion.

Which earth pressure coefficient is larger for the same soil?
A) Active (Kₐ)
B) Passive (Kₚ)
C) At-rest (K₀)
D) All equal

B) Passive (Kₚ) is much larger than active or at-rest coefficients.

The Rankine active earth pressure coefficient equals tan²(45° - _____)

Φ'/2 (half the effective friction angle)

What happens to lateral earth pressure when wall friction is considered?

Coulomb theory accounts for wall friction, modifying pressure coefficients from Rankine values.

A gravity retaining wall primarily resists lateral forces through its _____.

Mass (self-weight)

Which component acts as a vertical cantilever in cantilever retaining walls?
A) Heel
B) Toe
C) Stem
D) Key

C) Stem acts as the vertical cantilever element.

What is the minimum acceptable factor of safety against overturning?

2.0 (typical requirement)

True or False: The resultant force should intersect within the middle third of the base.

True. This prevents tensile stresses in unreinforced concrete bases.

Calculate Kₐ for soil with φ' = 32° using Rankine theory.

Kₐ = tan²(45° - 16°) = tan²(29°) = 0.307

Why do MSE walls use horizontal reinforcing elements?

To create a composite gravity structure with the reinforced soil mass.

The factor of safety against sliding equals _____ divided by driving force.

Resisting force (friction plus passive resistance)

What causes hydrostatic pressure behind retaining walls?
A) Soil weight
B) Groundwater
C) Surcharge loads
D) Seismic forces

B) Groundwater creates hydrostatic pressure that adds to earth pressure.

A uniform surcharge q produces additional lateral pressure of _____.

Kₐq (acting uniformly over the wall height)

True or False: Weep holes help reduce hydrostatic pressure behind walls.

True. They provide drainage to prevent water pressure buildup.

Sheet pile walls are most suitable for what type of applications?

Temporary excavations and waterfront structures requiring slender vertical elements.

The passive earth pressure coefficient Kₚ equals tan²(45° + _____)

Φ'/2

What increases when seismic forces act on retaining structures?
A) Only lateral pressure
B) Only vertical pressure
C) Both pressures
D) Neither pressure

A) Seismic forces increase lateral earth pressure through dynamic coefficients.

Maximum moment in a cantilever stem occurs at the _____.

Base (stem-foundation connection)

True or False: Counterfort walls have reinforcing elements on the face side.

False. Counterforts are on the backfill side; buttresses are on the face side.

Calculate total active force for H=10ft, γ=120pcf, φ'=30°.

Pₐ = ½KₐγH² = ½(0.333)(120)(100) = 2000 lb/ft

What defines the eccentricity limit for unreinforced concrete bases?

E ≤ B/6 (where B is base width)

An anchored sheet pile wall differs from cantilever type how?
A) Material
B) Support system
C) Soil type
D) Height only

B) Anchored walls have tie-backs or wales for additional support.

The coefficient of friction between concrete and sand typically ranges _____.

0.40 to 0.60

True or False: Passive resistance is often neglected in sliding calculations for conservatism.

True. Passive resistance may be reduced or ignored for conservative design.

What creates the composite action in MSE wall systems?

Horizontal reinforcement embedded in compacted backfill creates the composite gravity structure.

Bearing pressure at the toe equals ΣV/B(1 + _____)

6e/B (where e is eccentricity)

Which analysis method assumes a point of contraflexure below the anchor?
A) Fixed earth support
B) Free earth support
C) Rankine method
D) Coulomb method

B) Free earth support method assumes contraflexure point below anchor level.

A key projection from the base slab primarily increases _____.

Sliding resistance through additional passive pressure and friction area

True or False: Dynamic active force acts higher than static force on walls.

True. Seismic active force acts at approximately 0.6H instead of H/3.