The type of pile foundation that is installed in soft strata to build a stable foundation for heavy structures by the method of resistance is called:
- Afriction pilesCorrect
- Btension piles
- Cend bearing piles
- Dscrew piles
Solution
Concept
Friction piles carry load by skin friction (resistance) along their length in deep soft soil.
Formula
Qu = Qs = fs × As
Step-by-step solution
1. Soft strata extend to a large depth, so no hard layer is near. 2. End bearing piles need a hard layer at the tip, so they do not suit. 3. The pile carries the load by friction resistance between its surface and the soil. 4. These piles are called friction piles.
Explanation
When soft soil is very deep, the pile cannot rest on a hard layer. The load is carried by friction resistance along the pile surface. Such piles are called friction piles.
Why the other options are wrong
B: Tension piles resist uplift forces, not heavy downward loads in soft soil. C: End bearing piles transfer load to a hard stratum at the tip. D: Screw piles are a method of installation (screwing), not a load-resistance type.
Shortcut
Soft soil to great depth means friction piles. Hard layer at the tip means end bearing piles.
Common mistake
Choosing end bearing piles only because the structure is heavy.
Correct answer: A) friction piles