JKEARNEY
NOTES
SGM 323
,* Hh will the embankment settle ?
will it take to settle ?
*
towing
One dimensional consolidation
2
One dimensional consolidation
v
Stress h
h
v
v
Strain
h= 0
h= 0
q
Seepage
3
q
1
, entttttttt
very long Gt
EEE ? tmoouteheent
-
* stress vertical
& horizontal
* strain
only
in
vertical
direction .
E:# origin
,How much will it settle ?
=
* Test to find the stiffness ( E)
Consolidation test
To"IFnIf
FYI'is9pY:
to
pass
ment i.
Transducer)
µ
}
drainage
boundary
Top Cap
|8
Oedometer apparatus
We have the stiff to 4
Yw¥%aEe¥netuo"it .
horizontal strains
ring
prevent .
* ID test
* Drained conditions .
→ Consolidation
soils .
Theory only applies to
fully saturated
“Consolidation” is the dissipation of excess pore pressure.
B C
A
100kPa D
100kPa
0
100kPa
\
u=0 0<ue<100 ue=0
ue=100
'=0 '=0 ' <100 '=100
5
① U =
Hot Ue → excess pore water pressure .
↳ initial pore water
pressure
② O
'
=
g
-
U
2
,consolidationprocess.ba
A B C D
l
i÷÷÷÷÷
-
Ue A B C D
~
A B C D
How much
g
, Before Load After Load .
De
Vs =/
-
* Vu =
Vw ( Consolidated )
void ratio before
e.
loading
=
void ratio after
e.
loading
=
.
Ho
loading
before
height
=
height
in
AH
change
-
-
.
Verticalstrain.fer.is#=e.eeoeiee.J
MV
Coefficient of
compressibility
volume :
Mu=fEf/¥I7¥IstEaaer .
whymuno-tE.IE#
Mu
#
Young 's modulus under
Mv
Slype
• =
ID conditions .
ggnusntgraimneadu.us
↳
.
↳ NOT a constant .
O of
Ev
,Mechanism that control Is consolidation .
↳ Excess water
pore pressure .
Consolidation test
Oedometer apparatus
6
Void ratio vs. effective stress
µ
Loading stages
¥
⇐
unloading
-
Vertical effective stress
7
3
, MV
Coefficient of
compressibility
volume :
Mu=fgy/*I#rseofE * Stiffness
MT
|E
- -
slope
-
Mu
se
O Dou
'
o:
Ev
:÷÷÷÷÷÷÷÷÷÷÷÷±:i
Mu -
gg÷HI÷= leaks)
↳ This is our stiffness .
AH so ed Ho leg 4. lo )
-
- =
↳ settlement from Oedometer results .
, Void ratio vs. effective stress
""
"
-
-
-
°"
-
"
-
-
-
-
-
-
%c%%a⇐ ,
consolidated
Consolidated pre
-
-
-
-
-
←
→
.
Pressure .
To
Note the
gradient
change .
Only Virgin compression
* i line
*
Many unload reload lines 8 -
.
Pre consolidated is
highest
↳ the
pressure pressure
the
sample has
experienced .
Preconsolidation pressure ( 'max)
be less
Cpantnot
"
i
;i
hah 1
horizontal .
1 , halfway between .
i
tangential.to/-/
-
i 'max
'
OCR
i .
' vo
i
↳
← →
Cc OCR : Over consolidation
Ratio .
'
effective
O Max :
Highest
stress ever
experienced .
Gio : current
stress .
9
OCR =
I
} Normally consolidated .
↳ It will still settle .
OCR > I } Over Consolidated .
4
↳
Higher OCR ,
more stiff ,
less settlement .
