Consolidation Theory – Name of the Ratio s(t)/s(final) In one-dimensional consolidation of soils, the ratio of settlement at any time t to the final settlement is termed as which parameter?

Introduction / Context:
Consolidation describes the time-dependent compression of saturated clays under load as pore water drains and effective stress rises. Tracking how far the process has advanced at time t is essential for predicting settlements during construction and service life.

Given Data / Assumptions:

• One-dimensional consolidation under constant load.
• s(t) is settlement at time t; s(final) is ultimate settlement after full drainage.
• Soil is saturated and drainage path and boundary conditions are defined.

Concept / Approach:

The degree of consolidation, commonly denoted U, is U = s(t) / s(final). It measures progress toward the final state. It is related to the time factor Tv via solutions of Terzaghi’s consolidation equation and is independent of soil thickness scaling once Tv is fixed by c_v and drainage path.

Step-by-Step Solution:

Verification / Alternative check:

In lab oedometer tests, U can be inferred from dial readings; in the field, piezometers and settlement plates provide indirect checks corresponding to the same concept.

Why Other Options Are Wrong:

Coefficient of consolidation (c_v) controls the rate, not the fraction completed. 'Consolidation index' and 'consolidation of undisturbed soil' are not standard names for s(t)/s(final).

Common Pitfalls:

Confusing U with c_v; assuming U is linear in time (it is not, due to diffusion behavior).

Final Answer:

Degree of consolidation