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8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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LiuSongyu
Prof
.Dr.
InstituteofG
eotechnicalEn
gineering,
SoutheastUniversity,Nanjing,China
TheT-shaped
deepmix
edcolumn
applicationinsoftground
improvement
4th
inte
rnationalconferen
ceonGroutingand
DeepMixing
New
Orleans,Feb.1
8,2
012
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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Background
Fieldtest
Resultsand
analysis
Application
s
Conclusions
Outlineofth
epresen
tation
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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Twoeng
ineering
problems:Softsoil
groundan
dseismic
liquefactio
n
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B
ackground
Soil-ce
mentdeepm
ixingmethod(DMM)can
reduce
settlementandincreasestabilityofsoft
ground
Deepm
ixingmetho
diswidelyu
sedinsoft
ground
improvementinChina,e
speciallyin
highwa
y/railway/engineering.
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8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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Slurrysinglemixingmethod
resultin
gininsufficientsoil-cem
entmixing,
groutin
gspill,colum
nstrengthd
ecreasingwith
depth
Disadva
ntagesofconventionalDMMinC
hina(1)
Slurrysinglemixingmethod
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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spill
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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insuffic
ientmixing
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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Smallcolumnspacin
g,andcushionorgeosynthetics
reinforcedlayerare
oftenrequire
d,whichcau
se
highco
st.
Disadva
ntagesofordinaryDM
MinChina(2)
0.
8
1.
0
1.
2
1.
4
1.
6
1.8
010
20
30
40
Frequency(%)
C
olumnspacing(m)
875samples
Cushio
norgeosynthetic
s
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T-shape
ddeepmixingmethod
Ane
w
typeofdeepmixedcolumn
calle
dT-shapeddeepmix
ed(TDM)
colu
mnwasde
veloped(L
iue
t
al.,
2007a;2007b)
inordertosolvethe
aboveproblem
s
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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ATDM
columnh
asalarge
r
diam
eterinthe
shallowdepth,and
asmallerdiame
terinthe
deep
depth,creating
adeep-mi
xed
colum
nanalogo
ustotheletterT.
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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Them
ixingblade
sspreado
utward
where
enlargedcolumncap
swere
constr
ucted,whilemixingblades
shrunkinwardatthedesig
nedlevels
where
deep-depthcolumns
were
constr
ucted
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F
ieldtest
SketchoflocationofHusuzhe
Highway
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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Thehighwayhas6lanes,andtheembankment
heightwas~4m;
TDMs
itewas50m
wideand100
mlong;
Aconv
entionalDM
treatedsitewasplacedcloseto
itforcomparison.
In-situ
CPTUtestsandlaboratorytestswere
conduc
tedforsitecharacterization.
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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TDM
DM
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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CPTUtests
20
18
16
14
12
1086420
0
1
2
3
45
20
18
16
14
12
1086420
0
50100150200 2
018
16
14
12
1086420
05
0010001500
qt(MPa)
Depth(m)
fs(kPa)
u
2(kPa)
20
18
16
14
12
1086420
0
1
2
3
45
20
18
16
14
12
1086420
0
50100150200 2
018
16
14
12
1086420
05
0010001500
qt(MPa)
Depth(m)
fs(kPa)
u
2(kPa)
TDMsite
Conventional
DM
site
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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Typicale
ngineeringp
ropertiesofs
oilintestsites
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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Geometrydesignparame
tersofTDMco
lumns(unit:m)
Equivalentareare
placementratio
was0.108
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Geometrydesignparameters
ofconventionalDMcolumns(unit:m)
Areareplacementratiowas0.116
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I
nstallationofTDMcolum
n
Column
installation
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InstallationofconventionalDMcolumn
Column
installation
8/10/2019 Coloane AA - profil T - Liu PPT.pdf
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PortlandcementType32.5inChin
awasused.
water-c
ementratio(w
/c)was0.55,
injectionpressure
was0.3
MPa.
Cementcontent(cem
ent/wetsoil)was15%.
Rotatio
nspeedwasa
bout60r/min
.
Penetra
tionandretrie
valratewas~
0.8m/minfo
r0.5
mdiam
etercolumn,~0.6m/minfor
1mdiametercolumn.
Mixing
twicefor0.5m
diametercolumn,mixing
fourth
for1m
diametercolum
n.
Totalconstructiontim
eforTDMsitewas80%o
fthe
conventionalDMsite.
Column
installation
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TDMs
iteafter
columninstallation
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Sixcolu
mnsrandomly
selectedforco
ring28daysafter
installat
ion,unconfinedcompressive
testingwas
conduct
edforcoredsa
mpleswith50
mmdiameterand
100mm
length.
monitor
ing
TestP
rogram
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SomeR
esults-co
lumnquality
18
16
14
12
1086420
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Unconfiedcompressivestength(MPa)
Depth(m)
TDM
ConventionalDM
Qualitiesofthecolum
nsinstalledin
thetwosites
were
quitesim
ilar.
Lowove
rallCOVism
ainlyattributedtothedoub
le
mixingm
ethodadopte
dforcolumn
installation.
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Ground
settlement
Thefin
alreadingat290days
indicatesth
at
theto
talsettleme
ntoftheTD
Mcolumn
treate
dgroundw
asonly67%
ofthatofthe
conve
ntionalDM
columntrea
tedground.
30
0
25
0
20
0
15
0
10
0
5
000
30
60
90
120
150
180
2
10
240
270
300
012345
Settlementmm
TDM
convention
DM
Embankmentheightm
Tim
e(days)
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Lateralmovemen
t
Lateralmovementsof
soilbelowtoesofembankments
20
15
1050
0
10
20
30
40
20
15
1050
0
10
20
30
40
Late
ralmovement
mm
Depth(m)
TDM
9d
34d
49d
82d
98d
137d
164d
197d
225d
Lateralmovement
mm
Depth(m)
ConventionalDM
9d
34d
49d
82d
98d
137d
164d
197d
225d
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TDMw
asdevelopedin2004,hasbeenappliedinm
ore
than30
projects,withover1500000m3ofsoftsoils
treatedinhighwayapp
lications,from
2005-2011.
TDMapplication
s
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Diameterofdeep-depthcolumn(d)is0.5-0.7m,the
typicaldiameterofcon
ventionalDMcolumninChi
na.
Diameterofcolumnca
ps(D)is0.9-1
.2m,approxim
ately
2timesthatofdeep-depthcolumn.
Column
length(L)is1
1-25m,colum
ncaplength(L1)is
2-4mformostcases.
Column
spacing(S)is
1.7-3.2m,muchlargerthanthatof
theconventionalDMc
olumns(typically1.0-1.6m)
TDMapplication
s
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TDMcansavecementandconstru
ctiontime
comparedwiththeco
nventionalDM
.
Totalsettlementandt
hemaximum
lateralmovem
ent
oftheTDMs
itewere
only67%and31%thatof
the
convent
ionalDMsite
.
TDMm
ethodisamo
reeconomica
ndeffectivethan
theconventionalDMmethodforso
ftground
improve
mentC
onclusions
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Ac
knowled
gements
Hardw
orksofmyre
searchgroupandgradua
te
students.
Sponso
rshipsfromNationalScie
nceFoundat
ion
ofChina(No.
50879011)
andJiangsu
Province.
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Thank
you!