Geoscience Reference
In-Depth Information
Ground surface
Wooden
plate
Wire
netting
Liq uefied layer
Fig. 16.9. Previous study onthe effect of two types of countermeasures fora pipe
Sheet pile with
draining device
Soil cement
underground lattice
walls produced by
high pressure
jet grout
Sheet pile
(1) Uplift preventing sheet pile
(2) Soil improvement under structure
and sheet piling beside structure
Fig. 16.10. Remediation methods for existing underground structures
Yasudaetal.alsoconductedshakingtableteststostudytheeffectivenessofthetwotypes
ofcountermeasuresshowninFigure16.9inpreventingthemovementofliquefiedsoil.A
pairofwoodenplatesorwirenettingswasinstalledbesidethemodelpipe.Thesewooden
plates prevented uplift. Moreover, the wire nettings also prevented the uplift of the pipe
eventhoughtheexcessporewaterpressureratioatthebottomofthepipeincreasedupto
1.0, because the netting prevent the movement of liquefied soil grains under thepipe.
8.2. EXAMPLE OF TREATED STRUCTURES
8.2.1. A multi-service tunnel (partially quoted from JGS, 1998)
A countermeasure of driving sheet piles was applied to a multi-service tunnel, as shown
in Figure16.10(1). The sheet piles were driven besides the tunnel to the depth of 22.6m
toreachthelowernon-liquefiablelayer.Inthedesignofthicknessofthesheetpiles,earth
pressure,hydrostaticpressure,anddynamicwaterpressurewereconsidered.Thevertical
stability of the structure was also designed by considering the uplift force due to excess
pore pressure.
