Finite slope failures — if the critical slip surface emerges at the toe and passes through it, the mode of failure is termed:

Introduction / Context:
Classification of slope failure modes helps engineers interpret stability analyses and field observations. For finite slopes in homogeneous soils, circular or composite slip surfaces may intersect the slope in different locations, indicating toe, face, or base failures, each with distinct causes and remediation strategies.

Given Data / Assumptions:

• Homogeneous slope or slope analyzed with circular slip surfaces (e.g., method of slices).
• Failure surface intersects and passes through the toe of the slope.
• No reinforcement or retaining structures considered in the basic definition.

Concept / Approach:

When the critical slip circle exits at the toe, the mass primarily rotates and slides about a center located above the base, with the lowest restraint at the toe. This is identified as toe failure. By contrast, face failure surfaces exit on the slope face above the toe, and base failure surfaces pass below the toe into the foundation stratum, often when the foundation is weak or soft.

Step-by-Step Solution:

Verification / Alternative check:

Run alternative circles; if the most critical consistently crosses at the toe, the classification is robust. Field evidence like heave at the toe corroborates toe-type failure.

Why Other Options Are Wrong:

Face failure exits on the slope face above the toe.

Base failure passes below the toe through the foundation layer.

Generic “slope failure” does not indicate the location of exit.

Common Pitfalls:

Mislabeling due to not tracing the full slip surface; ignoring foundation stratigraphy which may shift the mechanism to base failure.

Final Answer:

toe failure