Assessing and managing the risk of earthquake-induced liquefaction to civil infrastructure - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 127

5.7 Infrastructure response to liquefaction: collapse of bridge deck due
to liquefaction-induced lateral spreading of embankments and reduced
lateral support to bridge piers following the Luzon, Philippines,
earthquake of July 1990 (courtesy EEFIT, UK).
on buildings housing administrative facilities, plant operations, personnel
and storage. Observations of earthquake damage show that compared to
ground shaking, landslides and tsunamis, liquefaction is less likely to cause
conventional collapse of buildings or fatalities (Bird & Bommer, 2004).
Liquefaction-induced damage to buildings typically includes foundation
settlement (Fig. 5.10) or tilting/displacement due to lateral spreading,
although structures with poor foundations can collapse due to liquefaction-
induced foundation movements.
If the residual shear strength of the liquefi ed soil beneath a foundation
is suffi ciently low (see Section 5.3.4), then bearing capacity failure will occur
causing a structure to uniformly settle or tilt, or to 'punch' through to stiffer
layers below. These types of failure are generally accompanied by heaving
of the ground around the foundation. The potential for a post-earthquake
bearing capacity failure can be estimated from simple static bearing capac-
ity formulae, by substituting the residual undrained shear strength of the
liquefi ed layers. Analysis of bearing capacity failure potential during an
earthquake needs to consider the effects of eccentricity of loading due to
the earthquake forces. Structures that are safe against bearing capacity
failure may still experience signifi cant settlements, depending on the strains
(shear and volumetric) that develop in the underlying soils.