1. 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.orgNiazi et al. 2010

2. 2 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 ( χ 2 test) Comparison of measured and evaluated soil unit weight,  t  LS regression, correlation coefficient  LS, principal component and reduced major axis regression  Higher order regression and residuals analysis Scope of Study

3. 3 qcqc u2u2 fsfs VsVs 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 I c,  t, OCR,  p ', K o, s u,  ', D R, G max q c, f s, u 2, V s Cone Penetration Test – a Hybrid Method

4. qtqt fsfs u2u2 VSVS Typical Cone Penetration Sounding 4

5. National Geotechnical Experimentation Site Riverside Campus, Texas A&M University Geotechnical Experimentation Site College Station Texas A&M University

6. Location of Clay and Sand Sites on Riverside Campus, Texas A&M University Clay Site Sand Site

7. Field Investigations at NGES Clay Site, Texas A&M University 1997 Twelve MCPT Six CPT Three SCPT Testing Program 1977 to 1995 Nine CPT 1995 to 1996 Three CPTu CPT: 10 cm 2 Cone Penetration Test CPTu:Piezocone Penetration Test MCPT:2 cm 2 Mini Cone Penetration Test SCPT: 15 cm 2 Seismic Piezocone Penetration Test BH:Borehole 15 m Clay Control 27 26 12 25 24 23 33 21 29 19 28 17 16 15 14 6 13 18 30 31 22 32 20 N 15 7 2 1 5 16 11 10 3 4 8 9 CPT CPTu MCPT SCPT BH Legend

8. Horizontal Variability of Tip Resistance Profiles Critical χ2 Value = 11.08

9. Spatial Variability Trend of Tip Resistance Profiles for 33 CPT Soundings Critical χ2 Value = 11.08

10. Horizontal Variability of Sleeve Friction Profiles Critical χ2 Value = 11.08

11. Spatial Variability Trend of Sleeve Friction Profiles for 33 CPT Soundings

12. Residuals of Principal Comp. Analysis of q t at 0.16 m Critical χ2 Value = 11.08

13. Residuals of Principal Comp. Analysis of q t at 10.56 m Critical χ2 Value = 11.08

14. Residuals of Principal Comp. Analysis of Tip Resistance at CPT4 Critical χ2 Value = 11.08

15. Residuals of Principal Comp. Analysis of Tip Resistance at MCPT13 Critical χ2 Value = 11.08

16. Results of Horizontal Variability Study 0 – 1.1 m 4.9 – 8.7 m 10.5 – 13.6 m

17. 1997 Twelve MCPT Six CPT Three SCPT Testing Program 1977 to 1995 Nine CPT 1995 to 1996 Three CPTu CPT: 10 cm 2 Cone Penetration Test CPTu:Piezocone Penetration Test MCPT:2 cm 2 Mini Cone Penetration Test SCPT: 15 cm 2 Seismic Piezocone Penetration Test BH:Borehole 15 m Clay Control 27 26 12 25 24 23 33 21 29 19 28 17 16 15 14 6 13 18 30 31 22 32 20 N 15 7 2 1 5 16 11 10 3 4 8 9 CPT CPTu MCPT SCPT BH Legend A A’ Results of Vertical Variability Study

18. 18  t = Total unit weight (kN/m 3 )  w = Unit weight of water (kN/m 3 ) q t = Cone tip resistance (kPa) f s = Sleeve friction (kPa) z = Depth (m)  vo ’ = Effective vertical overburden stress (kPa)  atm = Atmospheric pressure (kPa) Correlations: CPT Readings and Soil Unit Weight,  t Mayne et al. 2010

19. Measured and Evaluated Soil Unit Weight Profiles

20. Least Square Regression, Correlation Coefficient, 95% Confidence Bounds r = -0.2999r = -0.2508

21. 1997 Twelve MCPT Six CPT Three SCPT Testing Program 1977 to 1995 Nine CPT 1995 to 1996 Three CPTu CPT: 10 cm 2 Cone Penetration Test CPTu:Piezocone Penetration Test MCPT:2 cm 2 Mini Cone Penetration Test SCPT: 15 cm 2 Seismic Piezocone Penetration Test BH:Borehole 15 m Clay Control 27 26 12 25 24 23 33 21 29 19 28 17 16 15 14 6 13 18 30 31 22 32 20 N 15 7 2 1 5 16 11 10 3 4 8 9 CPT CPTu MCPT SCPT BH Legend Results of Vertical Variability Study

22. Least Square Regression, Correlation Coefficient, 95% Confidence Bounds p = 0.0001 p = 0.0002

23. Least Squares, Principal Component And Reduced Major Axis Regression Analyses

24. Higher Order Regression Analysis

25. 25 Horizontal and vertical variability of CPT readings for better site characterization CPT-based relationship for evaluating soil unit weight Conclusions Mayne et al. 2010

26. 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.orgNiazi et al. 2010

27. Depth (m) Very Stiff Clay Sand Very Stiff Clay Hard Clay (Shale)  t = 19.6 kN/m 3 s u = 110 kPa  t = 19.5 kN/m 3 s u = 140 kPa  t = 18.9 kN/m 3 s u = 160 kPa 0 2 4 6 8 10 12 14 16 18 After Briaud 2000 Stratigraphy at the NGES TAMU Clay Site

28. Autocorrelation of Residual Higher Order Regression