What is the primary advantage of a counterfort retaining wall?
- ARequires less excavation
- BSuitable for retaining high earth pressureCorrect
- CRequires less material compared to gravity walls
- DEasier to construct in hilly regions
Solution
Concept
Primary advantage of counterfort retaining walls
Formula
NONE
Step-by-step solution
1. Counterfort retaining walls feature thin vertical slabs supported at intervals by transverse counterforts. 2. This structural arrangement provides high stability and resistance, making it suitable for retaining high earth pressure over large heights. Answer: B
Explanation
Counterfort retaining walls use thin transverse webs or counterforts to connect the vertical stem to the heel slab, substantially increasing bending stiffness. This design effectively resists high bending moments and large lateral thrusts created by deep backfills. Consequently, these walls are economical and suitable for retaining high earth pressures, making option B correct.
Why the other options are wrong
A) Counterfort walls do not necessarily require less excavation than other retaining wall types. C) Saving material compared to gravity walls is not the primary advantage identified here. D) Counterfort walls involve complex formwork and are not easier to construct in hilly regions.
Shortcut
Counterfort retaining walls are economically designed for tall heights (>6 m) to resist high earth pressure.
Common mistake
Selecting option C by assuming material reduction is the primary advantage rather than its suitability for higher earth pressure.
Correct answer: B) Suitable for retaining high earth pressure