DAY 27 WORKSHEET LSGD (RCC Retaining Wall)

In a cantilever retaining wall, if the backfill is inclined at 10° to the horizontal, the resultant earth pressure will —

• Act normal to the backfill surface

• Act parallel to the backfill surface

• Act at an angle determined by surcharge and wall friction

• Always remain horizontal

For a retaining wall 6 m high, if the base width is insufficient to resist shear, a shear key is introduced. Its main function is to —

• Increase bearing area

• Reduce overturning moment

• Mobilize passive earth pressure in front of the toe

• Distribute load uniformly under the footing

If the resultant of forces acts beyond the middle third and causes tension under part of the base, the actual pressure diagram becomes —

• Triangular with maximum at toe only

• Trapezoidal with uniform compression

• Parabolic

• Uniform

In a counterfort wall, the counterforts act structurally as —

• Cantilevers fixed at toe

• Compression struts tying the stem and heel

• Shear connectors between stem and toe

• Diaphragm supports at the front face

If a retaining wall fails by overturning, the most effective design modification is —

• Increase wall height

• Increase base width toward heel side

• Reduce backfill unit weight

• Provide vertical reinforcement in stem

TRUE OR FALSE

In design for sliding stability, both frictional and passive resistances are considered, but passive resistance is ignored in seismic analysis.

TRUE OR FALSE

A buttressed retaining wall is preferred over counterfort type when backfill access must remain clear.

Assertion (A): Cantilever retaining walls are uneconomical beyond 7 – 8 m height. Reason (R): Because reinforcement demand and bending moments increase non-linearly with height.

The critical section for maximum bending moment in a cantilever retaining wall stem occurs at the __________.

The minimum factor of safety against sliding recommended for permanent retaining walls is __________.