The correct answer is: B. coefficient of compressibility of an over-consolidated clay is greater than that of a normally consolidated clay.
The coefficient of compressibility is a measure of how much a soil will compress under a given load. Over-consolidated clays have been subjected to a greater load in the past than they are currently experiencing, and as a result, they are more resistant to compression. Normally consolidated clays, on the other hand, have not been subjected to a significant load in the past, and as a result, they are more easily compressed.
Here is a more detailed explanation of each option:
- Option A: The coefficient of compressibility of an over-consolidated clay is less than that of a normally consolidated clay. This is incorrect because over-consolidated clays are more resistant to compression than normally consolidated clays.
- Option B: The coefficient of compressibility of an over-consolidated clay is greater than that of a normally consolidated clay. This is correct because over-consolidated clays are more resistant to compression than normally consolidated clays.
- Option C: The coefficient of compressibility is constant for any clay. This is incorrect because the coefficient of compressibility is a function of the soil type and the stress history of the soil.
- Option D: None of the above. This is incorrect because option B is the correct answer.