Which one of the following is a correct general consideration for a mechanically stabilized earth wall failure?
- ACompression in reinforcement
- BBearing capacity failureCorrect
- CShearing in the wall
- DPartly sliding of wall soil
Solution
Concept
An MSE wall is checked for external stability (sliding, overturning, bearing capacity, global stability) and internal stability (reinforcement rupture in tension, pullout).
Formula
FOS (bearing) = qult / qmax
Step-by-step solution
1. An MSE wall acts like a heavy gravity block of reinforced soil. 2. External checks: sliding of the whole block, overturning, bearing capacity of the foundation soil, and overall (global) slope stability. 3. Internal checks: tension rupture of the reinforcement and pullout of the reinforcement from the soil. 4. Of the given options, only bearing capacity failure is a standard check. 5. Answer: (B).
Explanation
MSE wall design checks external stability and internal stability. Bearing capacity failure of the foundation soil below the reinforced block is a standard external check. So option B is correct.
Why the other options are wrong
A: Reinforcement (strips or geogrids) carries tension, not compression. C: Shearing within the wall is not a standard named failure mode. D: Sliding is checked for the whole reinforced block, not for a 'partly sliding' soil.
Shortcut
MSE wall external checks = sliding, overturning, bearing, global. Internal checks = rupture and pullout.
Common mistake
Thinking reinforcement fails in compression. It always works in tension.
Correct answer: B) Bearing capacity failure