A Ph.D. Proposal Saeid Niazi Advisor:Lakshmi N. Sankar School of Aerospace Engineering
Fawad S. Niazi Geosystems Engineering Division Civil & Environmental Engineering Georgia Institute...
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Fawad S. Niazi Geosystems Engineering Division Civil & Environmental Engineering Georgia Institute of Technology April 27, 2010 Spatial Variability of CPT Data and Soil Parameters at NGES, Texas A&M www.clu-in.org Niazi et al. 2010 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 Tip q t (M Pa) Depth (m ) 0.0 0.1 0.2 0.3 Sleeve f s (M Pa)
description
Spatial Variability of CPT Data and Soil Parameters at NGES, Texas A&M. Fawad S. Niazi Geosystems Engineering Division Civil & Environmental Engineering Georgia Institute of Technology April 27, 2010. www.clu-in.org. Niazi et al. 2010. Scope of Study. - PowerPoint PPT Presentation
Transcript of Fawad S. Niazi Geosystems Engineering Division Civil & Environmental Engineering Georgia Institute...
Fawad S. Niazi
Geosystems Engineering DivisionCivil & Environmental Engineering
Georgia Institute of TechnologyApril 27, 2010
Spatial Variability of CPT Data and Soil Parameters at NGES, Texas A&M
www.clu-in.org Niazi et al. 2010
0
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0 5 10 15 20 25
Tip qt (MPa)
Dep
th (m
)
0.0 0.1 0.2 0.3
Sleeve fs (MPa)
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• Spatial variability of CPT readings for horizontal & vertical variability in soil profiles (all soundings, each 10 cm depth): Mean, min, max Moment statistics (variance, skewness, kurtosis) Residuals of principal comp. analysis of CPT readings (space and
depth) Test of normality (χ2 test)
• Comparison of measured and evaluated soil unit weight, gt
LS regression, correlation coefficient LS, principal component and reduced major axis regression Higher order regression and residuals analysis
Scope of Study
3
qc
u2fs
Vs
• Site characterization:
Conventional boring/sampling methods
Lab investigations on disturbed samples
• Cone penetration test:
Fast, economical, and continuous data
up to 4 separate readings in one sounding
Soil parameter interpretation
Ic, gt, OCR, p', Ko, su, ', DR, Gmaxqc, fs, u2, Vs
Cone Penetration Test – a Hybrid Method
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90
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0 5 10 15 20 25
Tip qt (MPa)
Dep
th (m
)
0.0 0.1 0.2 0.3
Sleeve fs (MPa)0 1 2 3 4
Porewater u2 (MPa)0 100 200 300 400 500
Shear Wave Vs (m/s)
qt
fs
u2
VS
Typical Cone Penetration Sounding
4
National Geotechnical Experimentation SiteRiverside Campus, Texas A&M University
GeotechnicalExperimentation Site
College StationTexas A&M University
Location of Clay and Sand Sites onRiverside Campus, Texas A&M University
Clay Site
Sand Site
Field Investigations at NGES Clay Site, Texas A&M University
1997• Twelve MCPT• Six CPT• Three SCPT
Testing Program1977 to 1995• Nine CPT1995 to 1996• Three CPTu
CPT: 10 cm2 Cone Penetration TestCPTu: Piezocone Penetration TestMCPT: 2 cm2 Mini Cone Penetration TestSCPT: 15 cm2 Seismic Piezocone Penetration TestBH: Borehole
15 mClay Control
27
26 12252423
33212919
2817161514
613
18
3031
22
32
20
N
15
7 2
15
1611
10
34
8
9
CPTCPTuMCPTSCPTBH
Legend
Horizontal Variability of Tip Resistance Profiles
0 3 6 9 12 15 18-18
-15
-12
-9
-6
-3
0
Tip Resistance, qc (MPa)
Dep
th (m
)
Mean+1 S.D.-1 S.D.
-1 0 1 2 3 4 5Skewness
0 3 6 9 1215 18Kurtosis
0 20 40 60 80 100Chi2 Value
Critical χ2 Value = 11.08
Spatial Variability Trend of Tip Resistance Profilesfor 33 CPT Soundings
02468
10121416
Tip
Res
ista
nce,
qc (M
Pa) Spatial Variability Trend of Tip Resistance w.r.t Distance from Clay Control
Mean+1 S.D.-1 S.D.
012345
Skew
ness
0369
1215
Kur
tosi
s
20 30 40 50 60 700
100200300400
Chi
2 Val
ue
Distance from Clay Control (m)
Critical χ2 Value = 11.08
Horizontal Variability of Sleeve Friction Profiles
0 0.2 0.4 0.6 0.8 1-18
-15
-12
-9
-6
-3
0
Sleeve Friction, fs (MPa)
Dep
th (m
)
Mean+1 S.D.-1 S.D.
-1 0 1 2 3 4 5Skewness
0 3 6 9 12 15 18Kurtosis
0 20 40 60 80100Chi2 Values
Critical χ2 Value = 11.08
00.10.20.30.40.50.60.70.8
Slee
ve F
rictio
n, f s (M
Pa) Spatial Variability Trend of Sleeve Friction w.r.t Distance from Clay Control
Mean+1 S.D.-1 S.D.
00.5
11.5
22.5
Skew
ness
0369
1215
Kur
tosi
s
20 30 40 50 60 700
60120180240300
Chi
2 Val
ue
Distance from Clay Control (m)
Critical χ2 Value = 11.08
Spatial Variability Trend of Sleeve Friction Profilesfor 33 CPT Soundings
Residuals of Principal Comp. Analysis of qt at 0.16 m
-1 0 1 2 3 4 5Skewness
0 3 6 9 1215 18Kurtosis
0 20 40 60 80 100Chi2 Value
0 3 6 9 12 15 18-18
-15
-12
-9
-6
-3
0
Tip Resistance, qc (MPa)
Dep
th (m
)
Mean+1 S.D.-1 S.D. Critical χ2 Value = 11.08
-5 0 50
1
2
3
4
5
6
7
8
Synthetic
Freq
uenc
y
Hist. of Res. 0.16 m Depth
-5 0 50
1
2
3
4
5
6
7
8
Actual
Hist. of Res. 0.16 m Depth
20 30 40 50 60 70-5
-4
-3
-2
-1
0
1
2
3Res. of PC Analysis Horiz. Var. at 0.16 m depth
Distance from clay control (meters)
Reg.
Res
idua
ls o
f Tip
Res
ista
nce
Residuals of Principal Comp. Analysis of qt at 10.56 m
-1 0 1 2 3 4 5Skewness
0 3 6 9 1215 18Kurtosis
0 20 40 60 80 100Chi2 Value
0 3 6 9 12 15 18-18
-15
-12
-9
-6
-3
0
Tip Resistance, qc (MPa)
Dep
th (m
)
Mean+1 S.D.-1 S.D. Critical χ2 Value = 11.08
20 30 40 50 60 70-1.5
-1
-0.5
0
0.5
1
1.5Res. of PC Analysis Horiz. Var. at 10.56 m depth
Distance from clay control (meters)
Reg
ress
ion
Res
idua
ls o
f Tip
Res
ista
nce
-2 0 20
1
2
3
4
5
Synthetic
Freq
uenc
y
Hist. of Res. 10.56 m Depth
-2 0 20
1
2
3
4
5
6
7
Actual
Hist. of Res. 10.56 m Depth
Residuals of Principal Comp. Analysis ofTip Resistance at CPT4
0 2 4 6 8 10 12 14-35
-30
-25
-20
-15
-10
-5
0
5
10Res. of PC Analysis: Vert. Var. of Tip Resis. CPT4
Depth (meters)
Reg
ress
ion
Res
idua
ls o
f Tip
Res
ista
nce
012345
Skew
ness
0369
1215
Kur
tosi
s
20 30 40 50 60 700
100200300400
Chi
2 Val
ue
Distance from Clay Control (m)
Critical χ2 Value = 11.08
-40 -20 0 200
5
10
15
20
25
30
35
40
Synthetic
Freq
uenc
yHist. of Res. at CPT4
-40 -20 0 200
20
40
60
80
100
120
Actual
Hist. of Res. at CPT4
Residuals of Principal Comp. Analysis ofTip Resistance at MCPT13
-4 -2 0 20
5
10
15
20
25
Synthetic
Freq
uenc
yHist. of Res. at MCPT13
-4 -2 0 20
5
10
15
20
25
30
Actual
Hist. of Res. at MCPT13
0 2 4 6 8-4
-3
-2
-1
0
1
2Res. of PC Analysis: Vert. Var. of Tip Resis. MCPT13
Depth (meters)
Reg
ress
ion
Res
idua
ls o
f Tip
Res
ista
nce
012345
Skew
ness
0369
1215
Kur
tosi
s
20 30 40 50 60 700
100200300400
Chi
2 Val
ue
Distance from Clay Control (m)
Critical χ2 Value = 11.08
Results of Horizontal Variability Study0 – 1.1 m
4.9 – 8.7 m
10.5 – 13.6 m
0 0.2 0.4 0.6 0.8 1-18
-15
-12
-9
-6
-3
0
Sleeve Friction, fs (MPa)
Dep
th (m
)
Mean+1 S.D.-1 S.D.
0 3 6 9 12 15 18-18
-15
-12
-9
-6
-3
0
Tip Resistance, qc (MPa)
Dep
th (m
)
Mean+1 S.D.-1 S.D.
1997• Twelve MCPT• Six CPT• Three SCPT
Testing Program1977 to 1995• Nine CPT1995 to 1996• Three CPTu
CPT: 10 cm2 Cone Penetration TestCPTu: Piezocone Penetration TestMCPT: 2 cm2 Mini Cone Penetration TestSCPT: 15 cm2 Seismic Piezocone Penetration TestBH: Borehole
15 mClay Control
27
26 12252423
33212919
2817161514
613
18
3031
22
32
20
N
15
7 2
15
1611
10
34
8
9
CPTCPTuMCPTSCPTBH
Legend
A
A’
Results of Vertical Variability Study
18
• gt = Total unit weight (kN/m3)
• gw = Unit weight of water (kN/m3)
• qt = Cone tip resistance (kPa)
• fs = Sleeve friction (kPa)
• z = Depth (m)
• vo’ = Effective vertical overburden stress (kPa)
• atm = Atmospheric pressure (kPa)
Correlations: CPT Readings and Soil Unit Weight, gt
18 18.5 19 19.5 20 20.517.5
18
18.5
19
19.5
20
20.5
21
21.5
22
22.5g
t = 1.95 g
w (
vo I/
atm)0.06 (f
s/
atm)0.06
y = 0.7522x + 4.7613
r = 0.8504
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
Raw DataFitted LS95% Confidence Bounds
18 18.5 19 19.5 20 20.517.5
18
18.5
19
19.5
20
20.5
21
21.5
22
22.5g
t (kN/m3) = 11.46 + 0.33 log(z) + 3.10 log(f
s) + 0.70 log(q
t)
y = 1.0880x - 0.9792
r = 0.8165
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
Raw DataFitted LS95% Confidence Bounds
Mayne et al. 2010
Measured and Evaluated Soil Unit Weight Profiles
10 15 20 25 30
gt (kN/m3) = 11.46 + 0.33 log(z) + 3.10 log(fs) + 0.70 log(qt)
Total Unit Weight, gt (kN/m3)
MeasuredEvaluated MeanEvaluated MinimumEvaluated Maximum
10 15 20 25 30-18
-16
-14
-12
-10
-8
-6
-4
-2
0
gt = 1.95 gw (vo I/atm)0.06 (fs/atm)0.06
Total Unit Weight, gt (kN/m3)
Dep
th (m
)
MeasuredEvaluated MeanEvaluated MinimumEvaluated Maximum
17 18 19 20 21 22 2312
14
16
18
20
22
24
26
gt = 1.95 g
w (
vo I/
atm)0.06 (f
s/
atm)0.06
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
Raw DataFitted LS95% Confidence Bounds
17 18 19 20 21 22 2312
14
16
18
20
22
24
26
gt (kN/m3) = 11.46 + 0.33 log(z) + 3.10 log(f
s) + 0.70 log(q
t)
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
Raw DataFitted LS95% Confidence Bounds
Least Square Regression, Correlation Coefficient,
95% Confidence Bounds
r = -0.2999 r = -0.2508
1997• Twelve MCPT• Six CPT• Three SCPT
Testing Program1977 to 1995• Nine CPT1995 to 1996• Three CPTu
CPT: 10 cm2 Cone Penetration TestCPTu: Piezocone Penetration TestMCPT: 2 cm2 Mini Cone Penetration TestSCPT: 15 cm2 Seismic Piezocone Penetration TestBH: Borehole
15 mClay Control
27
26 12252423
33212919
2817161514
613
18
3031
22
32
20
N
15
7 2
15
1611
10
34
8
9
CPTCPTuMCPTSCPTBH
Legend
Results of Vertical Variability Study
18 18.5 19 19.5 20 20.517.5
18
18.5
19
19.5
20
20.5
21
21.5
22
22.5g
t (kN/m3) = 11.46 + 0.33 log(z) + 3.10 log(fs) + 0.70 log(qt)
y = 1.0880x - 0.9792
r = 0.8165
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
Raw DataFitted LS95% Confidence Bounds
18 18.5 19 19.5 20 20.517.5
18
18.5
19
19.5
20
20.5
21
21.5
22
22.5g
t = 1.95 g
w (
vo I/
atm)0.06 (f
s/
atm)0.06
y = 0.7522x + 4.7613
r = 0.8504
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
Raw DataFitted LS95% Confidence Bounds
Least Square Regression, Correlation Coefficient,
95% Confidence Bounds
p = 0.0001 p = 0.0002
18 18.5 19 19.5 20 20.5 2118
18.5
19
19.5
20
20.5
21
21.5
22
22.5
23
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
gt = 1.95 g
w (
vo I/
atm)0.06 (f
s/
atm)0.06
Raw DataPrincipal Component RegressionLeast Square RegressionReduced Major Axis Regression
18 18.5 19 19.5 20 20.5 2118
18.5
19
19.5
20
20.5
21
21.5
22
22.5
23
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
gt (kN/m3) = 11.46 + 0.33 log(z) + 3.10 log(f
s) + 0.70 log(q
t)
Raw DataPrincipal Component RegressionLeast Square RegressionReduced Major Axis Regression
Least Squares, Principal ComponentAnd Reduced Major Axis Regression
Analyses
18 18.5 19 19.5 20 20.518
19
20
21
22
23
y = 0.2x3 - 11.4x2 + 209.1x - 1256.1
Measured gt (kN/m3)
Eval
uate
d g t (k
N/m
3 )
gt = 1.95 g
w (
vo I/
atm)0.06 (f
s/
atm)0.06
Raw Data3rd Order LS Regression95% Confidence Bounds
18 18.5 19 19.5 20 20.5-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
Total Unit Weight, gt (kN/m3)
Res
idua
ls
Residuals of 3rd Order Regression
18 18.5 19 19.5 20 20.518
19
20
21
22
23
y = 0.7x3 - 40.8x2 + 765.3x - 4761.8
Measured gt (kN/m3)
Eval
uate
d g t (k
N/m
3 )
gt (kN/m3) = 11.46 + 0.33 log(z) + 3.10 log(f
s) + 0.70 log(q
t)
Raw Data3rd Order LS Regression95% Confidence Bounds
18 18.5 19 19.5 20 20.5-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
Total Unit Weight, gt (kN/m3)
Res
idua
ls
Residuals of 3rd Order Regression
Higher Order Regression Analysis
25
•Horizontal and vertical variability of CPT readings for better site characterization
•CPT-based relationship for evaluating soil unit weight
Conclusions
18 18.5 19 19.5 20 20.517.5
18
18.5
19
19.5
20
20.5
21
21.5
22
22.5g
t = 1.95 g
w (
vo I/
atm)0.06 (f
s/
atm)0.06
y = 0.7522x + 4.7613
r = 0.8504
Measured Unit Weight (kN/m3)
Eval
uate
d U
nit W
eigh
t (kN
/m3 )
Raw DataFitted LS95% Confidence Bounds
Mayne et al. 2010
Fawad S. Niazi
Geosystems Engineering DivisionCivil & Environmental Engineering
Georgia Institute of TechnologyApril 27, 2010
Spatial Variability of CPT Data and Soil Parameters at NGES, Texas A&M
www.clu-in.org Niazi et al. 2010
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25
Tip qt (MPa)
Dep
th (m
)
0.0 0.1 0.2 0.3
Sleeve fs (MPa)
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