Civil Engineering Reference
In-Depth Information
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Seismic-induced landslide movement or failure.
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Slumping or minor shear deformations of embankments.
Tsunami or Seiche
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Settlement directly related to a tsunami or seiche. For example, the tsunami could cause
erosion of the soil underneath the foundation, leading to settlement of the structure. An
example of this condition is shown in Figs. 4.1 and 4.2.
Two additional conditions can cause settlement of a structure:
1.
Volumetric compression, also known as cyclic soil densification:
This type of set-
tlement is due to ground shaking that causes the soil to compress, which is often described
as
volumetric compression
or
cyclic soil densification.
An example would be the settlement
of dry and loose sands that densify during the earthquake, resulting in ground surface set-
tlement.
2.
Settlement due to dynamic loads caused by rocking:
This type of settlement is due
to dynamic structural loads that momentarily increase the foundation pressure acting on the
soil. The soil will deform in response to the dynamic structural load, resulting in settlement
of the building. This settlement due to dynamic loads is often a result of the structure rock-
ing back and forth.
These two conditions can also work in combination and cause settlement of the foun-
dation. Settlement due to volumetric compression and rocking settlement are discussed in
Secs. 7.4 and 7.5.
FIGURE 4.1
Overview of damage caused by a tsunami generated during the Prince William Sound earth-
quake in Alaska on March 27, 1964. Note the tilted tower in the background. (
Photograph from the
Steinbrugge Collection, EERC, University of California, Berkeley.
)
