Which foundation has an 80 cm pipe embedded at plinth level connecting to the foundation bottom (above 5 cm) with an interval of 1.5 m approximately?
Try it first: pick an option, then read the explanation.
Understanding the Described Feature
The question describes a very specific construction detail: a large diameter pipe (80 cm) embedded vertically within a foundation at regular intervals (1.5 m). This pipe connects the plinth level to just above the bottom of the foundation. This is not a standard structural element but is likely a feature for a specific purpose, such as inspection, drainage, or dealing with problematic soils.
Interpretation: This arrangement is most logically associated with a large, continuous shallow foundation where such features can be incorporated. The description points towards a specific type of construction sometimes used in areas with expansive soils or high water tables, where creating vertical, unreinforced shafts within the foundation can help relieve pressure or manage water.
Detailed Analysis of the Foundation Types
Let's evaluate which foundation type could accommodate such a feature.
(b) Strip / Pad foundation
Why it's the most plausible answer:
• Strip Foundation: A continuous strip of concrete supporting a load-bearing wall.
• Pad Foundation: An isolated slab of concrete supporting a single column.
Both of these are shallow foundations with significant width and length. It is structurally feasible to embed large vertical pipes within their mass at intervals. This kind of detail is sometimes used in specific ground conditions, for example, to create sand piles within a footing to accelerate consolidation or to act as inspection wells. Given the options, this is the only category where such a feature could be practically incorporated.
(a) Combined footing foundation
Why it's less likely: A combined footing is a type of pad footing that supports two or more columns. While it's a shallow foundation, the term "strip/pad" is a more general and fitting category for this unusual feature.
(c) Grillage foundation
Why it's incorrect: A grillage foundation is a dense arrangement of steel beams encased in concrete. It would be extremely difficult and impractical to embed a large 80 cm pipe through the multiple layers of steel beams.
(d) Pile foundation
Why it's incorrect: A pile foundation consists of long, slender columns (piles) driven or drilled into the ground. The feature described is part of a wide, shallow foundation, not a series of deep, narrow piles.