tall buildings, deep foundations - middle east experiences, 2009 1
DESCRIPTION
Tall BuildingsTRANSCRIPT
-
Coffey G
eotechnics
TA
LL BU
ILDIN
GS
, DE
EP
FO
UN
DA
TIO
NS
; MID
DLE
EA
ST
E
XP
ER
IEN
CE
S
The 2009 Terzaghi Oration
Harry Poulos
Coffey G
eotechnics
OU
TLIN
E
D
esign Process for H
igh-Rise B
uildings
Em
irates Twin Tow
ers Project
Investigations
D
esign
Load tests
Tower foundation perform
ance
Burj D
ubai
Foundation design
Load tests
Foundation performance
G
old Coast B
uilding
Henry D
avid Thoreau
Walden (1854)
If you have built castles in the air,Your w
ork need not be lost;That is w
here they should be.N
ow put the foundations under them
.
FOU
ND
AT
ION
DE
SIG
N
PR
OC
ES
S
Site characterization
Geology
S
tratigraphy
Quantification of relevant geotechnical param
eters. B
ased on:
In-situ testing
Laboratory testing
Load testing
-
FOU
ND
AT
ION
DE
SIG
N
PR
OC
ES
S
Foundation Type & Layout.
Usually piles or piled raft
Based on:
Foundation loadings
Design criteria
C
onstruction issues
Material availability
FOU
ND
AT
ION
DE
SIG
N
PR
OC
ES
SD
esign Issues1.
Ultim
ate capacity2.
Settlem
ent3.
Differential settlem
ent & tilt
4.D
ynamic behaviour
5.E
arthquake response6.
Structural strength of foundation elem
ents7.
Durability
LOC
AT
ION
OF D
UB
AI
PR
OJE
CT
S
Em
irates Site -1996
-
SIT
E P
LAN
& B
OR
EH
OLE
S
INV
ES
TIG
AT
ION
PR
OG
RA
M
23 boreholes, up to about 80m
depth (maxim
um)
Trial pits
SP
T in upper layers
Undisturbed sam
pling
Water sam
ples
Perm
eability tests
Pressurem
eter tests
Vertical seism
ic shear wave profiling
U
niformity borehole testing
LAB
OR
AT
OR
Y T
ES
TIN
G
C
onventional laboratory & field tests
S
pecialized testing
Site uniform
ity testing (geophysical)
Cyclic triaxial testing
Effects of repetitive w
ind loading
Stress path triaxial testing
Deform
ation parameters
C
NS
testing
Ultim
ate shaft friction
Resonant colum
n testing
Dynam
ic shear modulus &
damping
GE
OT
EC
HN
ICA
L PR
OFILE
&
MO
DE
L FOR
EM
IRA
TE
S S
ITE
Eu MPa
E' MPa
fs kPafb M
Papu M
Pa
Silty Sand40
3018
0.20.1
Silty Sand125
10073
1.51.5
Calcareous Sandstone
700500
2002.3
2.3
Silty Sand125
100150
1.91.9
Calcisiltite
500400
4502.7
2.7
"90
80200
2.02.0
"700
600450
2.72.7
-
FOU
ND
AT
ION
TY
PE
S
Towers
Piled raft foundations
Podium
Piles, pile groups
LOA
D T
ES
T P
RO
GR
AM
B
elow each tow
er:
C
ompression test to 3000t, L=40m
, d=0.9m
Static tension test: L=25m
, d=0.6m or 0.7m
C
yclic tension test
Lateral load test
Class A
predictions made using assessed design
parameters
PR
ED
ICT
ION
ME
TH
OD
S
A
xial Response
N
on-Linear boundary element analysis
P
IES
program
Lateral Response
N
on-Linear boundary element analysis
E
RC
AP
program
Cyclic Tension Test
Non-Linear boundary elem
ent analysis
SC
AR
P program
TH
E E
MIR
AT
ES
PR
OJE
CT
, D
UB
AI
-
SE
TU
P FO
R C
OM
PR
ES
SIO
N
PILE
TE
ST
S(-2.00) (-0.50)(-1.50)(-5.00)(-10.0)(-16.0)(-20.0)(-25.0)(-30.0)(-36.0)(-40.0)
Working
platform
Unit1
-Silty
sand
Unit2
-C
alcareoussandstone
Unit4
-C
alcisiltite
Unit3
-Silty
sand
2030
1285
900
Ground
anchors
Reference
beams
Footprintoftheground
anchorsatthe
groundlevel
No.1
Extensom
eter
No.4
Straingauges
22N
osof
groundanchors
3000t LOA
D T
ES
T W
ITH
R
EA
CT
ION
AN
CH
OR
S
Emirates Project, D
ubai
LOA
D-S
ET
TLE
ME
NT
CU
RV
ES
FO
R P
ILE P
3(H)
010
2030
400
5000
10000
15000
20000
25000
30000
Applied Load (kN)
Settlement(m
m)
PredictedM
easured
PR
ED
ICT
ED
& M
EA
SU
RE
D
AX
IAL LO
AD
DIS
TR
IBU
TIO
NS
05000
1000015000
2000025000
30000
-40-38-36-34-32-30-28-26-24-22-20-18-16-14-12-10 -8 -6 -4 -2 0 2
Level DMD (m)
Measured
(15000kN
)M
easured(23000
kN)
Predicted
Load
(kN)
-
LOA
D-M
OV
EM
EN
T C
UR
VE
S
FOR
UP
LIFT T
ES
T
-35-30
-25-20
-15-10
-50
0 1000
2000
3000
4000
5000
6000
Applied Load (kN)
Measured
Predicted
Uplift(m
m)
ULT
IMA
TE
SH
AFT
FRIC
TIO
N
FRO
M T
ES
TS
0100
200300
400500
600700
50 40 30 20 10 0
Depth (m)
Ultim
ateSkin
FrictionkPa
Design
valuesD
educedfrom
P3(hotel)
piletest(com
pression)D
educedfrom
P1(hotel)
piletest(tension)
Deduced
fromP3
(office)pile
test(compression)
Deduced
fromP1
(office)pile
test(tension)
ME
AS
UR
ED
& P
RE
DIC
TE
D LA
TE
RA
L LO
AD
-DE
FLEC
TIO
N C
UR
VE
S
-10-5
05
1015
2025
Applied Load (kN)
0 25 50 75
100
125
150
175
200
Displacem
ent(mm
)
PredictedM
easuredM
easured
ME
AS
UR
ED
& P
RE
DIC
TE
D LA
TE
RA
L D
EFLE
CT
ION
vs DE
PT
H
-24
-22
-20
-18
-16
-14
-12
-10 -8 -6 -4 -2 0 2
Level DMD (m)
-1.00
2.04.0
6.08.0
10.012.0
Measured
Predicted(L
oad=150
kN)
Deflection
(mm
)
-
AS
SE
SS
ME
NT
OF
PR
ED
ICT
ION
S
Class A
predictions were in fair agreem
ent
Cyclic loading effects not w
ell-predicted
Assisted by:
Com
prehensive investigation data
Modern m
ethods of lab & field testing
S
traight-forward m
echanisms of behavior
EM
IRA
TE
S T
OW
ER
S-
FOU
ND
AT
ION
SY
ST
EM
S
1.5m thick raft
102 piles for office
91 piles for hotel
1.2 & 1.5 m
piles to 40-45 m
DE
SIG
N M
ET
HO
DO
LOG
Y
Limit State A
pproach
Ultim
ate Limit State:
S
tatic loads
Repetitive w
ind loads
Serviceability Lim
it State:
S
ettlements : m
ax. 150mm
A
ngular rotation: max. 1/350 long-term
TO
WE
R FO
UN
DA
TIO
N
AN
ALY
SE
S
GA
RP
program for piled rafts
U
ltimate Lim
it State:
U
sed both factored & unfactored pile capacities
M
any load combinations
S
erviceability Limit S
tate
Long-term settlem
ents -GA
RP
S
hort-term m
ovements (w
ind) D
EFP
IG for axial &
lateral stiffness of individual piles in group
Passed on to structural engineer for overall analysis
-
LOA
D C
OM
BIN
AT
ION
S
U
ltimate Lim
it State:
1.25G + 1.5Q
1.2G
+ 0.4Q + W
u
0.8G = W
u
S
erviceability Limit S
tate:
G + 0.4Q
Total of 18 load cases per tower
PILE
INT
ER
AC
TIO
N D
IAG
RA
M :
OFFIC
E T
OW
ER
DY
NA
MIC
FOU
ND
AT
ION
R
ES
PO
NS
E
Required for seism
ic & w
ind response
D
ynamic stiffness &
damping from
dynamic
pile group analysis via Gazetas approach
M
ATLA
B program
developed for evaluation
SE
ISM
IC E
FFEC
TS
Liquefaction:
Low
very low risk
Ground A
mplification of seism
ic motions:
C
ategory B assessed
modest am
plificationP
otential for Site S
ettlements:
A
ssessed to be low, 5-10m
m under design
earthquake, unlikely to cause excessive downdrag
loads on piles.
-
PR
ED
ICT
ED
SE
TT
LEM
EN
T
CO
NT
OU
RS
FOR
OFFIC
E T
OW
ER
05
1015
2025
3035
4045
500 5 10 15 20 25 30 35 40 45 50
y axis (m)
xaxis
(m)
100
110
110
110 120
120
120
120
130
130
130
110
110
55
100
Predicted Max.
Settlement =
134 m
m
PR
ED
ICT
ED
SE
TT
LEM
EN
T
CO
NT
OU
RS
FOR
HO
TE
L TO
WE
R
05
1015
2025
3035
4045
500 5 10 15 20 25 30 35 40 45 50
y axis (m)
xaxis
(m)
110
55
105
115
115
115
115
115
125
125
125
105
105105
105
105
Predicted Max.
Settlement =
138 m
m
TH
E E
MIR
AT
ES
PR
OJE
CT
, D
UB
AI
TH
E E
MIR
AT
ES
PR
OJE
CT
, D
UB
AI
-
ME
AS
UR
ED
& P
RE
DIC
TE
D T
IME
-S
ET
TLE
ME
NT
BE
HA
VIO
R
OFFIC
E
TO
WE
R
01
23
45
67
89
1011
12
50 40 30 20 10 0
Settlement (mm)
Predicted
T112T
111
1998T
ime
(months)
ME
AS
UR
ED
& P
RE
DIC
TE
D T
IME
-S
ET
TLE
ME
NT
BE
HA
VIO
R
HO
TE
L T
OW
ER
01
23
45
67
89
1011
12
50 40 30 20 10 0
Settlement (mm)
Predicted
T4
T15
1998T
ime
(months)
Measured
ME
AS
UR
ED
SE
TT
LEM
EN
T
CO
NT
OU
RS
H
OT
EL T
OW
ER
T1
T2
T3
T4
T5
T6
T7
T8
T9
T10
T11
T12
T13
T14
T15
T16
T17
T18
T19
T20
-8.0
-7.5
-8.3
-6.3
-6.0
-8.7
-7.9
-8.2
-8.3-7.2
-6.5
-5.8
-6.9-6.2
-7.3
-6.5
-7.4
-5.3
-7.4 -7.0
-6
-7
-7
-7
-7
-7
-7
-8
-6
-8-8
SE
NS
ITIV
ITY
OF IN
TE
RA
CT
ION
FAC
TO
RS
T
O A
NA
LYS
IS A
SS
UM
PT
ION
S
12
510
2050
100
0.10
0.2
0.3
0.4
Interaction Factor D
s/d
12534 CurveN
o.M
odulusof
Layer
belowM
Pa
Modulus
ofSoilbetw
eenPiles
toN
ear-PileValues
9090200700700
1.05.05.05.01.0
12345
Allow
ances made for:
Stiffer soil between piles
Stiffer soil below pile tips
Interaction is generally reducedM
arkedly.
Assum
ptions have a MA
JOR
influence on computed
interaction effects.
-
EFFE
CT
OF A
NA
LYS
IS A
SS
UM
PT
ION
S O
N
CO
MP
UT
ED
SE
TT
LEM
EN
T
0 20 40 60 80
100
120
140
160
OR
IGIN
AL
CA
SE
2C
AS
E 3
CA
SE
4C
AS
E 5
Settlement mm
Hotel Tow
er
TH
E E
MIR
AT
ES
PR
OJE
CT
, D
UB
AI
SO
ME
CO
MM
EN
TS
M
ajor efforts to obtain good site characterization
Design values of skin friction higher than
previously used in UA
E
CN
S direct shear testing proved very useful
Test pile behaviour reasonably w
ell-predicted
Foundation behaviour not well-predicted, but at
least conservative
TA
LLES
T B
UILD
ING
S (2000)
-
Dubai -2006
BU
RJ D
UB
AI T
OW
ER
Site P
hotograph S
eptember
2003
EA
RLY
CO
NS
TR
UC
TIO
N
July 2005
-
GE
OT
EC
HN
ICA
L PE
ER
R
EV
IEW
-SC
OP
E
Review
geotechnical information
D
evelop geotechnical model independently
Independent review
of Hyder foundation design
Independent calculations for foundation stability, settlem
ent, differential settlement
A
ssessment of pile load test data and final design
parameters.
Close cooperation betw
een Coffey &
Hyder m
aintained.S
ite visits, examination of site and borehole cores.
SIT
E C
HA
RA
CT
ER
IZA
TIO
N
30 boreholes
SP
T
60 PMT tests in 5 boreholes
6 standpipe piezom
eters
Geophysics
cross-hole tomography
SIM
PLIFIE
D P
RO
FILE4
Silty Sand
6C
alcarenite
17C
alcareous Sandstone
4.5G
ypsiferous Sandstone
40C
onglomeritic C
alcisiltite
22.5C
alcareous/Conglom
eritic
>47C
laystone/Siltstone
Base of Tow
er Raft
Base of Tow
er Piles
Typical C
ores 66m
depth
-
Typical C
ores 88m
depth
LAB
OR
AT
OR
Y T
ES
TIN
G
Conventional tests:
C
lassification (various)
UC
S
Point Load Index
M
odulus
Chem
ical
LAB
OR
AT
OR
Y T
ES
TIN
G
Advanced tests:
S
tress path triaxial
Resonant colum
n
Cyclic undrained triaxial
C
yclic simple shear
C
NS
HY
DE
R P
ILE D
ES
IGN
P
AR
AM
ET
ER
AS
SE
SS
ME
NT
S
kin friction via UC
S correlations &
CN
S test
data
Modulus value for settlem
ent prediction via correlations w
ith SP
T & U
CS
, pressuremeter,
shear wave velocity (w
ith allowance for strain
levels)
Non-linear behaviour via stress path tests
Judgem
ent employed
-
INIT
IAL P
ILE D
ES
IGN
Tow
er:
196 piles, 1.5m diam
eter, 47.5m long
Podium
:
750 0.9m diam
eter piles, 30m long
R
aft:
3.7m thick (tow
er)
HY
DE
R S
ET
TLE
ME
NT
P
RE
DIC
TIO
NS
R
EP
UTE
linear
P
IGLE
T -linear
V
DIS
P -linear &
non-linear
A
BA
QU
S
non-linear 3D FE
A
PR
ED
ICT
ED
LOA
D-
SE
TT
LEM
EN
T C
UR
VE
S50m
long 1.5m diam
. pile
0 10 20 30 40 50 60 70 80 90
010
2030
4050
6070
8090
Settlement m
m
Load MN
Hyder
Coffey
HY
DE
R -IN
ITIA
L TO
WE
R
SE
TT
LEM
EN
T P
RE
DIC
TIO
NS
Analysis
Settlem
ent mm
(Flexible cap)S
ettlement m
m(R
igid cap)R
EPUTE
p66
p)56
PIG
LET
-45
VD
ISP
-62
ABAQU
S72
46
-
CO
FFEY
IN
ITIA
L TO
WE
R
SE
TT
LEM
EN
T E
ST
IMA
TE
S
FLAC
(Axisym
metric)
73 m
m(m
aximum
)
P
IGS
74 m
m (m
aximum
)
LOA
D T
ES
T P
RO
GR
AM
3 static com
pression tests (1.5m dia.)
V
arious toe levels (35-55m long)
1 static com
pression test (0.9m dia.)
S
haft grouted
1 cyclic compression test (0.9m
dia.)
1 static tension test (0.9m dia.)
1 lateral load test
LOA
D T
ES
T P
RO
GR
AM
-O
UT
CO
ME
S1.5m
piles loaded to 2 times W
L0.9m
piles to 3.5 times W
L
No piles appeared to be approaching failure
S
kin friction values in excess of design assumptions
S
haft grouting effective, but not necessary
End bearing resistance not fully m
obilized
Axial stiffness greater than predicted
C
yclic axial loading had little effect
Lateral stiffness greater than predicted
CO
MP
AR
ISO
NS
S
KIN
FR
ICT
ION
-120
-100
-80
-60
-40
-20 0 20
0100
200300
400500
600700
800900
Skin Friction kPa
RL (DMD)
Original Design
Msd. Low
er Bound
Msd. Upper Bound
Recomm
ended (Hyder)
-
ME
AS
UR
ED
& P
RE
DIC
TE
D
PILE
HE
AD
ST
IFFNE
SS
ES
0
1000
2000
3000
4000
5000
6000
TP1TP2
TP3TP4
TP5TP6
Stiffness MN/m
Test Pile Number
At W
orking Load
At M
aximum
Load
Calc. At W
orking Load
ME
AS
UR
ED
& P
RE
DIC
TE
D
PILE
HE
AD
ST
IFFNE
SS
ES
Possible reasons for stiffer than expected
behaviour:
Use of polym
er drilling fluid.
Interaction between test pile &
reaction piles:
Analysis estim
ated that this interaction could cause a reduction in test pile settlem
ent of about 30%
With this allow
ance, axial stiffness more consistent
with E
mirates experience
TO
WE
R P
ILE LA
YO
UT
PR
ED
ICT
ED
SE
TT
LEM
EN
T
PR
OFILE
-
PR
ED
ICT
ED
SE
TT
LEM
EN
T
CO
NT
OU
RS
P
IGS
AN
ALY
SIS
LOA
D T
ES
TS
ON
WO
RK
S
PILE
S
Load tests carried out on some w
orks piles
Behaviour (axial) even better than test piles
P
redicted settlements could be conservative,
although group settlement depends on
stiffness of underlying layers
Measured T
ime-S
ettlement
Wing A
Measured T
ime-S
ettlement-
Wing B
-
Measured T
ime-S
ettlement
Wing C
Measured S
ettlement C
ontours -A
ugust 2006
Com
parison with P
redictions
Assum
ing 40% D
L and LL = 20% of D
L, in August 2006, applied load is about 33%
of design load
For linear behaviour, maxim
um predicted
settlement is:
H
yder22 m
m
Coffey
25 mm
M
easured16 m
m
Com
parison with P
redictions
Latest m
easurements:
Maxim
um m
easured settlement tow
ards the end of construction is about 40m
m
-
CO
MP
LET
ED
RA
FT
CO
NS
TR
UC
TIO
N P
RO
GR
ES
S
Early 2006Early 2007
September 2007
Gold C
oast Project -A
rtique
A
28 storey building on the G
old Coast
S
tructural Engineer
designed a fully piled to rock foundation system
P
iling contractor engaged C
offey to assess feasibility of piled raft
B
ased on results of feasibility, piling contractor engaged C
offey to optimize
piled raft design
Analysis of P
iled Raft
Feasibility
Detailed D
esign S
erviceability
Optim
ization
Detailed D
esign S
trength
-
OriginalD
esign
Con
tiguou
s bored pile wall
13
6 piles
foun
dedon
rock
Shear join
t between
core and podiu
m Slab0
.7m
thick
PEATY CLAY(SO
ME SAND)F-St
SANDD
SANDY CLAY (H) /CLAYEY SAND
MD
SAND WITH
SOM
E GRAVEL
MD
SANDY GRAVEL
METASILTSTO
NESW
0-5
-10
-15
-20
-25
-30
-35
-40
DESCRIPTION
Av.SPT
kPa(RAFT)
MPa
SuE
ss
E(PILES)
MPa
u p(RAFT)
MPa
kPafs
b fM
Pa
ASSUMED
BASE OF RAFT
60-
905.4
120100
9.9
1080
80.5
2022
0.7
60-
905.4
120100
9.9
14250
251.5
4060
2.0
25-
37.52.25
5048
4.1
100-
1509.0
200100
10.0
--
2000-
2000-
10.0RL (m)
SANDD-VD
M
Geotechnical
Model
Feasibility Results
Indicated that a raft foundation alone w
ould have a factor of safety of approxim
ately 10 for ultim
ate loading
Settlem
ents would govern. E
stimated to be of
the order of 35mm
to 60mm
The num
ber of piles would be of the order of
140
as per the foundation design supplied by contractor. H
owever, piles only 18m
long not 35m
Serviceability C
ase
123 piles (13 less)
M
aximum
raft settlem
ent of 44m
m
Maxim
umdifferentialsettlem
ent of 10m
m (1/400)
-
Outcom
es
N
umber of piles reduced by 10%
(13 piles)
Pile length reduced from 35m
to 18m
Total pile length reduced by 2767m
Settlement criteria (both total and
differential) satisfied
Potential variations in pile stiffness
compensated for by raft
CO
NC
LUS
ION
S
G
round conditions in Dubai are challenging for very tall
buildings
Modern m
ethods are being employed for:
In-situ testing
Laboratory testing
A
nalysis & design m
ethods
Sim
pler methods essential for checks on advanced num
erical analyses
U
se of piled rafts can lead to foundation economy
W
ith benefit of experience, predictive capabilities are im
proving
BU
T, reluctance remains to m
easure foundation performance
AC
KN
OW
LED
GE
ME
NT
S
Artique P
roject
Paran M
oyes
Frances Badelow
John S
mall
E
mirates P
roject:
Patrick W
ong
Jeff Forse
Paul G
ildea
Bob Lum
sdaine
Strath C
larke
Leanne Petersen
Burj D
ubai:
Frances Badelow
M
uliadi Merry
P
atrick Wong