Which statement is TRUE for ground improvement?
- APre-compression of soil is generally effective in only clays and siltsCorrect
- BCompaction piles can be used for cohesive soils
- CDeep mixing can be used for rocks
- DDensification by vibrofloating is not effective for cohesionless soils
Solution
Concept
Suitability of improvement methods
Step-by-step solution
1. Pre-compression (preloading) removes settlement of compressible clays and silts, so it is generally effective only there. 2. Compaction piles and vibroflotation are for cohesionless soils; deep mixing is for soft soils, not rock.
Explanation
Preloading works by consolidation of fine-grained soils.
Why the other options are wrong
B, C and D misstate the suitability of the methods.
Shortcut
Preloading → clays/silts; vibro → sands.
Correct answer: A) Pre-compression of soil is generally effective in only clays and silts