Base failure of a finite slope
- AOccurs when soil below the level of toes is strong
- BOccurs when there is a weak zone in upper part of a slope
- COccurs when soil below the level of toes is relatively soft and weakCorrect
- DIs a most common failure and occurs in relatively steep slopes
Solution
Concept
Base failure
Step-by-step solution
1. A slope can fail by slope failure, toe failure or base failure. 2. Base failure occurs when the soil below the toe level is soft and weak, so the slip circle passes below the toe.
Explanation
In base failure the critical slip surface goes into the foundation soil below the toe because that soil is relatively soft. It generally occurs in flat slopes of soft cohesive soils, while toe failure is common in steep slopes.
Shortcut
Slope failure: weak zone in the slope. Toe failure: steep slope. Base failure: soft soil below the toe.
Common mistake
Choosing toe failure (D) because it is more common.
Correct answer: C) Occurs when soil below the level of toes is relatively soft and weak