Civil Engineering Reference
In-Depth Information
FIGURE 3.21
View of the bottom of a Kawagishi-cho apartment building located in Niigata, Japan. The
building suffered a liquefaction-induced bearing capacity failure during the Niigata earthquake on June 16,
1964. (
Photograph from the Steinbrugge Collection, EERC, University of California, Berkeley.
)
as essential facilities, because they provide necessary transportation routes for emer-
gency response and rescue operations. A bridge failure will also impede the transport
of emergency supplies and can cause significant economic loss for businesses along the
transportation corridor. There are several different ways that bridges can be impacted
by liquefaction. For example, liquefaction beneath a bridge pier could cause collapse
of a portion of the bridge. Likewise, liquefaction also reduces the lateral bearing, also
known as the passive resistance. With a reduced lateral bearing capacity, the bridge
piers will be able to rock back and forth and allow for the collapse of the bridge super-
structure. A final effect of liquefaction could be induced downdrag loads upon the
bridge piers as the pore water pressures from the liquefied soil dissipate and the soil
settles.
Figure 3.25 shows the collapse of the superstructure of the Showa Bridge caused by
the 1964 Niigata earthquake. The soil liquefaction apparently allowed the bridge piers
to move laterally to the point where the simply supported bridge spans lost support and
collapsed.
3.4.3 Waterfront Structures
Port and wharf facilities are often located in areas susceptible to liquefaction. Many of these
facilities have been damaged by earthquake-induced liquefaction. The ports and wharves
often contain major retaining structures, such as seawalls, anchored bulkheads, gravity and
cantilever walls, and sheet-pile cofferdams, that allow large ships to moor adjacent to the
