Consolidation Concepts – Identify the Incorrect Statement (Single Best Answer) Consider the following statements about one-dimensional consolidation parameters and curves. Identify the statement that is NOT correct.

Introduction / Context:
Consolidation theory explains time-dependent compression of saturated clays under load. A precise understanding of definitions is essential for interpreting oedometer results and settlement predictions for embankments and foundations.

Given Data / Assumptions:

• Standard one-dimensional consolidation in an oedometer.
• Effective stress increases cause void ratio reduction.
• Loading–unloading cycles define characteristic segments of the e–log σ′ curve.

Concept / Approach:

(a) The coefficient of compressibility a_v is defined by a_v = −Δe/Δσ′ (decrease in void ratio per unit increase of effective stress) → correct. (b) Degree of consolidation U is the fraction of ultimate settlement realized at time t, often expressed as a percentage → correct. (c) The time factor T_v = c_v * t / H_d^2 is dimensionless → correct. (d) The 'virgin' compression curve is the initial loading segment before preconsolidation is exceeded; segments during unloading and reloading are known as the recompression (or swelling/rebound) curve, not the virgin curve → therefore (d) is incorrect.

Step-by-Step Solution:

Verification / Alternative check:

Classical e–log σ′ plots display a steeper virgin compression line beyond preconsolidation stress and a gentler recompression line during unloading/reloading cycles.

Why Other Options Are Wrong:

(a), (b), and (c) are correct; hence selecting 'None of these' would be incorrect because one statement is indeed wrong.

Common Pitfalls:

Confusing virgin and recompression segments; mixing total and effective stress terminology in consolidation parameters.

Final Answer:

The initial curve on either side of the point of unloading and reloading is called the 'virgin' curve