columna resonante 3
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dynamic measurements
Richard Jardine
Dynamic soil properties seminar
17th March 2010
© Imperial College LondonPage 1
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Scope for comparisons• -, ,
Needs big shaking tests or seismic arrays, plus powerful lab!
• Lab versus field at smaller strains: body wave velocities, and
•
static versus dynamic lab
• Key points:
Sampling disturbance and in-situ macro-structure
Imposed stress & strain paths
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u non- near response rom ana ys s o
Example: Lotung Taiwan - operating since 1985
Figures from Elgamel et al (1995)
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Seismic array analysis
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Interpretion: Vs velocities, G values & damping curves
Experience: “Lab Vs and G values typically well below field values,
although decay curves may match better”
RC Lab trends
RC Lab trend
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•
sand structure? Usual to rely on in-situ testing..
• Clays and mudrocks also give problems, how should they
be sampled?
• Consider historical progression of Imperial College work
• See that im rovements in sam lin and testin allow us
to be happier about comparisons between lab and field
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C l ti l b d ( tl BRE) fi ld
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Correlating lab and (mostly BRE) field
At ICP pile research sites:
• anons ar , on on c ay
• Pentre, deep, low OCR, glacio-lacustrine clay-silt,
rops re
• Dunkerque, medium dense marine sand, Northern
- , ,
• London clay: Terminal 5 Heathrow
Also Crag and London Tertiaries at Sizewell – Hight et al (1997)
ry ng o n a an e on on c ay e av our
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ry ng o n a an e on on c ay e av our Conventional tests can’t match geophysics
(expressed as Eu equivalent to 3G)
ardine et al (1985)
BRE reflective field geophysics
Plate, SB Pressuremeter &Back Analysis profiles
And conventional laborator
triaxial tests
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R i i th i t f li it
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Recognising the importance of non-linearity
‘ ’
New insights offered by locally instrumented triaxial tests
Canons Park & Bell Common
Reference ‘small strain’
Thin walled samples, UU tests
Electrolevel axial strain sensors
Stiffnesses @ 0.01% strainStiffer response when:
Ko reconsolidated
Conventional
testing
High quality rotary core samples
0.001 0.01 0.1 1 1
Behaviour over non-linear range
© Imperial College LondonPage 9
,u , no c ear near e as c reg on..
i t li k l b d fi ld L d l b h i
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rying to link lab and field London clay behaviour
ardine et al (1985)
UU Eu(0.01) profile
Static ‘back-analysis’ < Eu(0.01) < Dynamic 3Ghh
From Canons Park
CUKo triaxial tests on rotary samples
Any elastic range?
Geophysics
Insitu Ghh AbbissWhat about anisotropy?
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Si il li t d f L d l fi ld
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Similar non-linear trends from London clay field
es s Jardine et al (1985)
Re-interpretation of Cooke Price and Tarr (1979)Stresses ad acent to ile from theor strains from in- lace inclinometers
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Similar trends from non linear Self Boring
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Similar trends from non-linear Self Boring
Pressuremeter & UU and CUKo
triaxial tests; Jardine (1992)
• Importance of strain level is clear
-
range from various experiments
• No reliable Gmax comparisons
• o ana ys s o an so ropy
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Subsequent lab developments and new tools
• Better local strain sensors
• IIS Tokyo LDTs (Goto et al 1991), better electrolevel gauges; Hall effect
devices & LVDT systems
• Hollow Cylinder (HCA) Resonant Column Apparatus: more uniform
, u , -
• Bod waves: multi-directional S-wave bender element and P-wave
measurements
• Locally instrumented static Hollow Cylinder Apparatus (HCA)
•
IC Resonant Column HCA
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IC Resonant Column HCA,
=
di = 38 mm
o
vh
External and semi-local
instrumentation (corrected
for apparatus compliance)
100 mm
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ome checks made with local au es
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, ,
glacial lacustrine clay-silt
BRE Seismic CPT tests’ Gvh
compared by Chow 1997 with:
n piston samples: Gvh mode
riaxial tests Connolly (1997)
Fair match, closer if thinner wall,
harp edged, stainless steelampling tubes used?
s in Bothkennar stud ….
P t d l OCR l ilt
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Pentre: deep, low OCR clay-siltan ors ona ear es s s ow a r agreemen a
mall strains for silt (& sands) Porovic (1995)
Greatly different strain rates: RC > 104 faster
Resonant Column
TS Scatter
Torsional shear
easuring anisotropic elastic stiffness in triaxial tests
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For cross-anisotropic materialeasuring anisotropic elastic stiffness in triaxial testsav
θaar vh
θ E E E
r h==
arahv θννν ==
θaar vhGGG ==
r r rr hh θθνννν === Shibuya (1992). See Kuwano & Jardine (1998) or Lings et al (2000)
σaResonant columnGvh
Vertically & horizontally
polarised BE tests:Hi h resolution τaθ giving Ghh and Ghvstress-strain
probing tests:σ
θ
σr
en er e ements ,hh hv
σ
changing σ΄v andσ΄r individually
a a(v)
σ
σr
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D k i t i l b tiff t d
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Dunkerque: anisotropic lab stiffness sets and
BRE seismic CPT profiles:Chow (1997), Kuwano (1999), Jardine et al (2003)
0 100 200 300 400 500 600 700
Elastic stiffness, MPa
Dunkerque laboratory profiles for dense sand and field sesimic profile
Also, good agreement for
reconstituted sands’ Gvh0
between:
Eu from TXC tests'
• esonan co umn• Bender element
•
15 D e p
t h , m
E'h from TX testsGvh from TX BE testsGhh from TX BE tests
Gvh from field seismic CPT testsEu from TXC testsE'v from TXC testsPorovic (1995),
20
rom tests
Connolly & Kuwano (1999)
© Imperial College LondonPage 19
Gvh Gvh Ghh E’h E’v Eu
Seismic CPT -------------------- All laboratory------------------------
Dunkerque trends over non linear range;
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Dunkerque trends over non-linear range;
m te scope o tr ax a testsDunkerque dense sand secant shear stiffness data OCR = 2
=
1400
1600
Stiffness characteristics
1000
1200
Undrained triaxial extension with stress state;
Kuwano and Jardine (200
800
G / p '
400
600 Torsional shear
0
200
© Imperial College LondonPage 20
0.001 0.01 0.1 1
Es, %
Measuring anisotropic stiffness in HCA tests
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For cross-anisotropic materialMeasuring anisotropic stiffness in HCA testsav
= θ
νννaar vh
==
θ
E E E r h
==
arahv θ
ννν ==
GGG == νννν ===
Resonant column tests Can also apply
σaResonant columnGvh
- vh
Static uniaxial probes for
‘τaθ
a s ness o ssonratio’ components
σθ
σr
Bender elements G ,Ghh hv
Uniaxial tests to failure
a a(v)
a
σr
(1997)
© Imperial College LondonPage 21 r
r
Application or London clay in Heathrow T5 project
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pp y p j
PhDs: Gasparre, Nishimura, Minh – see Imperial College website
Papers: - Geotechnique February/March 2007; IS-Atlanta 2008
Block sampling
-
© Imperial College LondonPage 22
Two deep rotary-cored boreholes
down hole
eo h sics
London clay T5 lab testing in Gvh mode
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London clay T5 – lab testing in Gvh modeesonan o umn an ors ona ear s mura ,
BE tests and static probing tests by Gasparre (2005) and Nishimura (2006)
Multiple tests on rotary
Resonant column
cores and block samples
Torsional shear Resonant Column
Gmax typically 20%
higher than Torsional
Shear Gvh at γ = 3x10-5
5 Field & laboratory
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5 Field & laboratory
v pro s
fter Nishimura (2006)
ood agreement down to 20m
ab Bender Element < RC Gvh
ab RC < seismic Gvh in
eeper layers
Laboratory BE Gvh
Laboratory HCA RC Gvh
esult of macro-fabric? Seismic Gvh:
Page 24r imperfect sampling & testing?
Triaxial stress path testing
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p g
,
PC
load
cellPC
load
cell
CRSP air-oil
interface
CRSP air-oil
interface
volumegaugevolumegauge
air-water
interfaceexternalLVDT
air-water
interfaceexternalLVDT
pore pressurepore pressure
© Imperial College LondonPage 25
trans ucercell pressure
transducer
trans ucercell pressure
transducer
Triaxial tests by Gasparre (2006)
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437
Triaxial tests by Gasparre (2006)
436
k P a ]
Search for kinematic yield surfaces
Study of possible stress history effects
435
' a
Y1 0 300 400 500 600
p' [kPa]
]
434
0.0000 0.0005 0.0010 0.0015 0.0020 0.0025 0.0030
εa [%]-100
q [ k P
A3
C &
B2(c)
B2(a)
0.12
0.16
-
0.08
0.00
0.04
Y2
1 s en o e as c range
Page 26
. .
εv [%]
2 characteristics & other features
More HCA tests
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More HCA tests
niaxial probing tests inar y n - n
x o , n anceElectro-level & Proximitylocal strain measurements
for four strain components
amples - h = 200 mm- i = mm
- do= 100 mm
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Stiffness anisotropy from HCA tests
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Stiffness anisotropy from HCA testsn ax a pro ng es s o a ure: ree en ca samp es
300
Uniaxial tests
Stiffness [MPa]
E'h
200 [ M P a ]
∆σθ
∆σz
σ r = cons an
p' = 280kPa
E z a n d G
z ∆τ
zθ
.
E'v
100 e c a n t E
θ ,
Gvh
© Imperial College LondonPage 2810
-310
-210
-110
0
Absolutte strains εθ, εz and γzθ [%]
0
Anisotoropy from static and dynamic lab tests
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py y
Lab data match general trends from in-situ geophysics
More divergence at depth: macro-fabric or sampling?
0 200 400
Young's Moduli [MPa]
0 100 200
Shear moduli [MPa]
0 100 200
Bulk modulus, K [MPa]
C
B2(c)
x x xx
10
[ m ]
B2(b)
x x x20
D e p t h
B2(a)
Bxx x x x
30
Ev' (TX)
Ev' (HCA)
Gvh
(BE)
Ghh (BE)
A3(2)
© Imperial College LondonPage 29
40Eh' (TX)
Eh' (HCA)
Gvh (RC)
Gvh (Static)
Continuing work:
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Continuing work:Lab & geophysical testing of Cretaceous and Jurassic
Mudrocks
x or c ay - comp e e
Gault Clay – underway
Kimmeridge - underway
HCA & advanced triaxial testing by Amandine Brosse, Ramtin KamalHossieni, micro-fabric & geology by
Stephen Wilkinson
Page 30
CONCLUSIONS:
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Aim: synthesize lab & field dynamic properties over the full range
ee s power u a es s p us se sm c array a a, or o er nverse e
analysis. Can expect strong rate effects in non-linear range.
‘Reasonable’ matches possible between field and (possibly slightly softer)
lab stiffness, if advantage is taken of improvements in:
Sampling quality
Understanding anisotropy & strain level effects
Test interpretation
Note the great value of appropriate field geophysical testing
© Imperial College LondonPage 31
Acknowledgements
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esearc sponsors an par ners: , an o ers
work has been referred to including:
John Burland
Fiona Chow
Apollonia Gasparre
David Hi ht
Nguyen Anh-Minh
Satoshi NishimuraEsad Porovic
Tim Connolly
© Imperial College LondonPage 32
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© Imperial College LondonPage 33
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TC-29
ISSMGE
-
© Imperial College LondonPage 35
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,
successor to:
SIP-London (1997)
IS-Torino 1999
IS-Lyon (2003)IS-Atlanta (2008)
© Imperial College LondonPage 36
Professor Alan Bishop
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