Section 4: Soil and Water Conservation Engineering
Soil Mechanics
Subtopic: Engineering properties of soils
Question Statement:
According to Terzaghi's principle of effective stress, the shear strength and volumetric deformation of saturated soils are uniquely governed by:
Options:
(A) Effective stress ($\sigma' = \sigma - u$), which is total stress minus pore water pressure
(B) Total normal stress ($\sigma$) alone, regardless of pore water pressure
(C) Neutral stress / pore water pressure ($u$) alone
(D) Atmospheric barometric pressure acting on the ground surface
Answer Key:
A
Step-by-Step Solution & Explanation
Terzaghi established that all measurable effects of a change of stress, such as compression, distortion, and a change of shearing resistance, are exclusively due to changes in the effective stress $\sigma' = \sigma - u$. Option A is correct.