Geoscience Reference
In-Depth Information
Belt conveyer
Chemical
grout
Gravel drain
Deep mixing
(1) Soil improvement by deep
mixing and gravel drain
(2) Soil improvemant by chemical grout
Stone
fill
Cement-mixed
sand
Existing
revetment
Stone fill
New steel pile
(4) Strengthen by steel piles and stone fill
(3) Pre-mixing
Fig. 16.7. Remediation methods for existing sea walls
Figure16.7(1)showsoneofthequaywalls,whichwastreatedbythedeepmixingmethod
and the gravel drain method.
7.2.2. Port of Oakland (partially quoted from TC4, 2001)
Stone columns were installed at the Seventh St. Marina Terminal, Port of Oakland, Cali-
fornia,afteritwasdamagedinthe1989LomaPrietaearthquake,tomitigateliquefaction
riskduringfutureearthquake.A12mwidezoneofstonecolumnswasconstructedalong
the rear of the wharf. The stone column extended mostly through 4 to 7m thick exist-
ing perimeter rock fill dike used to retain hydraulic filling of the terminal area. The dike
rests on a 4.3 to 8.2m thick hydraulically-placed sand base. These sands are predomi-
nantly clean and liquefiable. Underneath the dike and sand base, there is an 11 to 25m
thick layer of native silty and clayey sand. The upper 1.5m of this layer was considered
potentially liquefiable.
7.2.3. Ishikari Port (partially quoted from Kawamura et al., 2001)
At a quay wall in Ishikari Port, the ground behind the quay wall was improved with
permeation grouting as illustrated in Figure16.7(2). The quay wall is a steel sheet-pile
wall with tie wires. Though many tie wires intersect at a corner of the quay wall, the
permeation method could be applied.
7.2.4. Kobe Port (partially quoted from TC4, 2001)
Many port-related facilities in Kobe Port were severely damaged during the 1995 Kobe
earthquake. At the time of the earthquake, the port had 186 quay walls, about 90%
of which were caisson walls. Most of these caisson walls moved toward the sea by a
maximum about 5m and an average of 3m, and inclined about four degrees toward the
sea. Several restoration methods were applied after the earthquake. One was the premix
method, as shown in Figure16.7(3). A temporary sheet pile was installed in the ground
