Question

Consider the following properties, identify the one(s) that are varied with a variation in effective stress.

i) Compressibility

ii) Shear strength

iii) Permeability

1. i and ii
2. i and iii
3. ii and iii
4. i, ii and iii

Answer 1

Correct Answer - Option 4 : i, ii and iii

Concept:

Effective stress in soil:

• Effective stress is the ratio of force at the contact of particles of soil to the total area.
• Karl Terzaghi was the first to propose this effective stress definition. In soil mechanics, this is a critical concept.
• Effective stresses affect a number of properties, including volume change, shearing strength, permeability, and compressibility.

It cannot be obtained practically but we can calculate the effective stress by measuring total stress and pore water pressure as:

Total stress (σ) = effective stress (σ’) + pore water pressure (u)

Effective stress (σ’) = Total stress (σ) - pore water pressure (u)