Which is the group of Raymond piles?
Try it first: pick an option, then read the explanation.
Understanding Pile Classification by Installation Method
Concrete piles can be classified based on how they are made and installed. This is a fundamental distinction in foundation engineering.
Cast-in-situ Piles: The pile is constructed in its final location. A hole is bored or driven into the ground, and this hole is then filled with fresh concrete.
• Cased: A permanent steel shell or "casing" is left in the ground, and the concrete is poured inside it.
• Uncased: A temporary casing is used to form the hole and is withdrawn as the concrete is poured.
Precast Piles: The pile is manufactured in a factory, cured, and then transported to the site where it is driven into the ground like a nail.
Detailed Analysis of Raymond Piles
A Raymond pile is a specific, proprietary type of driven pile with a distinct construction method.
(a) Cased cast in situ concrete pile
Why it's correct: The Raymond pile process involves driving a thin, corrugated steel shell into the ground using a collapsible steel core called a mandrel. Once the desired depth is reached, the mandrel is withdrawn, leaving the hollow steel shell in the ground. This shell is then inspected and filled with concrete. Because the steel shell remains in the ground as a permanent part of the pile, it is a classic example of a cased cast-in-situ pile.
Other Examples of Cased Cast-in-situ Piles:
The Raymond pile belongs to a family of similar piles, including:
- Swage pile
- Mac-Arthur pile
- Monotube pile
Functional Classification of Piles
Piles can also be classified by how they transfer load to the ground, regardless of their construction method.
- End Bearing Piles: Transfer most of their load through their tip (end) to a strong soil layer or bedrock.
- Friction Piles: Transfer most of their load through skin friction along the length of the pile shaft in soils where a strong bearing layer is very deep.
- Compaction Piles: Used in loose granular soils to densify the soil by vibration, rather than to carry a direct load.
- Tension or Uplift Piles: Used to resist pulling-out forces, anchored by friction or under-reams.