Consider the statements P, Q and R.

P: Compacted fine-grained soils with flocculated structure have isotropic permeability.

Q: Phreatic surface/line is the line along which the pore water pressure is always maximum.

R : The piping phenomenon occuring below the dam foundation is typically known as blowout piping.

Which of the following option(s) is/are CORRECT?

Explanation:

Statement P:

"Compacted fine-grained soils with flocculated structure have isotropic permeability."
True - Fine-grained soils compacted on the dry side of optimum moisture content tend to have a flocculated structure (random arrangement). This structure provides approximately equal permeability in all directions (isotropic permeability), as confirmed by the provided explanation.

Statement Q:

"Phreatic surface/line is the line along which the pore water pressure is always maximum."
False - The phreatic line represents the topmost flow line below which seepage occurs in a dam body. However, pore water pressure is not maximum along the phreatic line; rather, it is atmospheric at this level. The maximum pore water pressure occurs below the phreatic line, not along it.

Statement R:

"The piping phenomenon occurring below the dam foundation is typically known as blowout piping."
False -

• Piping phenomenon refers to the erosion of soil due to excessive seepage forces.

• The correct term for piping failure below the dam foundation is "heave" or "boiling", not blowout piping. Blowout typically refers to failure due to excessive water pressure in confined aquifers rather than dam foundation piping.