Diagram of horizontal ground oscillation caused by liquefaction in the cross-hatched zone decoupling the surface layers from the underlying ground.
Loss of Bearing Strength
|Diagram of structure tilted due to loss of bearing strength When the soil supporting a building or other structure liquefies and loses strength, large deformations can occur within the soil which may allow the structure to settle and tip||
Liquefaction weakens the soil reducing foundation support which allows heavy structures to settle and tip (Youd, 1992).
In many cases, the weight of a structure will not be great enough to cause the large settlements associated with soil bearing capacity failures described above.
However, smaller settlements may occur as soil pore-water pressures dissipate and the soil consolidates after the earthquake.
These settlements may be damaging, although they would tend to be much less so than the large movements accompanying flow failures, lateral spreading, and bearing capacity failures.
The eruption of sand boils (fountains of water and sediment emanating from the pressurized, liquefied sand) is a common manifestation of liquefaction that can also lead to localized differential settlements.
Increased Lateral Pressure on Retaining Walls
If the soil behind a retaining wall liquefies, the lateral pressures on the wall may greatly increase. As a result, retaining walls may be laterally displaced, tilt, or structurally fail, as has been observed for waterfront walls retaining loose saturated sand in a number of earthquakes.