Geoscience Reference
In-Depth Information
Fig. 11.24. Effect of soilcrust thickness and shear strength on (a) liquefaction
settlemets,and (b) degraded static factors ofsafety
while thecorresponding seismicsettlements become lower than a criticalvalue, i.e.
2
.
50
a
max
T
2
Z
liq
·
q
ρ
dyn
<ρ
dyn
,
c
=
0
.
016
·
N
·
(11.17)
5
.
14
C
u
Thevalueof
)
cr
correspondstothatclaycrustthicknesswherethebearingcapacity
obtainedbythecompositefailuremechanismshowninFigure11.3becomesequaltothat
for a wedge-type failure mechanism developing exclusively within the clay crust. Thus,
itmaybereadilycomputedfromEq.11.6inconnectionwiththeanalyticalmethodology
outlinedinTable11.2.Forquickreference,Figure11.25showsthevariationof
(
H
/
B
(
H
/
B
)
cr
FS
max
deg
,
C
u
/γ
H
and
and
B
. In this case also, the
frictionangleofthesandhasarelativelyminoreffectandwaskeptconstant
ρ
dyn
,
c
/
B
versus 1
/
=
q
/(
5
.
14
C
u
)
ρ
o
/
35
o
(ϕ
o
=
)
.
Inpracticalapplications,thischartmaybeusedforapreliminaryevaluationoftheallow-
able average bearing pressure
q
=
q
all
in terms of the specific soil profile characteristics
/
ρ
o
/
(
H
B
and
C
u
)andtheseverityofshakingexpressedthrough
B
.Nevertheless,incase
ρ
dyn
,
c
,
that the corresponding critical seismic settlement
obtained from the same figure
