Undisturbed Shear Strength vs. Remoulded Shear Strength in Cohesive Soil

Undisturbed Shear Strength:
- The undisturbed shear strength of a cohesive soil is the shear strength measured in its natural state.
- It is the maximum shear resistance that the soil can offer under undrained conditions.
- The undisturbed shear strength is the result of the natural formation of the soil and the stresses it has experienced over time.

Remoulded Shear Strength:
- The remoulded shear strength of a cohesive soil is the shear strength measured after the soil has been disturbed or remoulded.
- Remoulding the soil causes the particles to rearrange and change the soil structure, which affects its strength properties.
- The remoulded shear strength is usually lower than the undisturbed shear strength.

Ratio of Undisturbed to Remoulded Shear Strength:
- The ratio of the undisturbed shear strength to the remoulded shear strength is a measure of the sensitivity of the soil to disturbance.
- It is an important parameter for evaluating the stability of slopes and foundations in cohesive soils.
- If the ratio is greater than 1, it indicates that the soil is less sensitive to disturbance and can offer more resistance to shear forces.
- If the ratio is less than 1, it indicates that the soil is more sensitive to disturbance and its strength properties can be significantly affected by remoulding.
- A ratio of 1 indicates that the soil has the same shear strength properties whether it is undisturbed or remoulded.

Therefore, the correct answer is option C - the ratio of undisturbed shear strength to remoulded shear strength in cohesive soil under undrained conditions is greater than 1.