What are the three modes of failure in retaining wall design?

In retaining wall design, the three primary modes of failure are overturning, sliding, and bearing capacity.

Overturning occurs when the wall tilts or rotates about its base due to lateral earth pressures exceeding the wall's resisting moment. This is particularly critical for tall walls that must withstand significant lateral loads from the retained soil. Ensuring that the structure has adequate weight and stability is crucial in preventing such a failure.

Sliding, on the other hand, refers to the horizontal movement of the wall due to the lateral forces from the soil and water behind it. This mode of failure can often be addressed through adequate friction at the base of the wall, additional weight, or the use of keying mechanisms.

Bearing capacity failure occurs when the soil beneath the retaining wall can no longer support the loads transmitted by the wall, leading to settlement or instability. This can be influenced by factors such as soil type, moisture content, and the wall's overall design and loading conditions.

Understanding these three failure modes is essential for designing safe and effective retaining walls that can withstand the various forces acting upon them.