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Comparing Liquefaction Evaluation Methods Using Penetration- V S Relationships

Comparing Liquefaction Evaluation Methods Using Penetration- V S Relationships. Ronald D. Andrus Clemson University with P. Piratheepan, Brian S. Ellis, Jianfeng Zhang, and C. Hsein Juang U.S.-Taiwan Workshop on Soil Liquefaction National Chiao Tung University, Hsin-Chu, Taiwan

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Comparing Liquefaction Evaluation Methods Using Penetration- V S Relationships

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  1. Comparing Liquefaction Evaluation Methods Using Penetration-VS Relationships Ronald D. Andrus Clemson University with P. Piratheepan, Brian S. Ellis, Jianfeng Zhang, and C. Hsein Juang U.S.-Taiwan Workshop on Soil Liquefaction National Chiao Tung University, Hsin-Chu, Taiwan November 3-5, 2003

  2. Acknowledgements • The U.S. Geological Survey (USGS) and the South Carolina Department of Transportation (SCDOT) funded part of this work • Many individuals assisted with data collection, including: T. L. Holzer, M. J. Bennett, J. C. Tinsley, & T. E. Noce of USGS T. N. Adams of SCDOT T. J. Casey & W. B. Wright of Wright Padgett Christopher W. M. Camp & E. Cargill of S&ME, Inc. F. Syms of Bechtel Savannah River, Inc. S. L. Gassman of University of South Carolina

  3. Database • Data from California, South Carolina, Canada, Japan, and Taiwan • 45 Holocene (< 10,000 years) soil layers, and 55 older soil layers • Only sands with FC≤ 20 % or Ic ≤ 2.25 • All measurements below water table • Both non-liquefied and liquefied sites

  4. Criteria for Selecting Data • Thick, uniform soil layers based on CPT data, or several SPT and VS measurements • Penetration test within 6 m of Vs test • At least 2 Vs measurements and corresponding test intervals within layer • Time history records used for Vsdetermination have “easy picks” for shear wave arrivals; if time histories are not available, at least 3 Vs measurements within layer

  5. Corrected S-Wave Velocity where VS1 = stress-corrected VS (VS1)cs = stress- and fines content-corrected VS Kcs = fines content correction factor (Juang et al. 2002) Ka1 = age correction factor (Andrus & Stokoe 2000)

  6. Three Curves for Evaluating Liquefaction Resistance

  7. SPT – VS Relationships forHolocene Sands Age, years < 500 > 500 Non-liquefied Liquefied

  8. CPT - VS Relationships for Holocene Sands Age, years < 500 > 500 Non-liquefied Liquefied

  9. CPT – SPT Relationships for Holocene Sands Age, years < 500 > 500 Non-liquefied Liquefied

  10. VS – CRR Equation(Andrus & Stokoe 2000) where CRR7.5cs = CRR curve for MW = 7.5 and FC≤ 5 % (VS1)csa1 = corrected VS

  11. New SPT – CRR Equation where CRR7.5cs = CRR curve for MW = 7.5 and FC≤ 5 % (N1)60cs = corrected SPTblow count

  12. New CPT – CRR Equation where CRR7.5cs = CRR curve for MW = 7.5 and IC≤ 1.64 (qc1N) cs = corrected CPTtip resistance

  13. NEW CRR Curves Based on Penetration – VS Equations

  14. Comparison of CRR Curves with Liquefaction Probability = 26 %

  15. SPT - VS Relationships for Older Sands Ten Mile Hill (Liquefied)

  16. CPT - VS Relationships for Older Sands Non-Liq Liq Merritt Sand Wando Ten Mile Hill Dry Branch Taiwan Sand

  17. CPT – SPT Relationships for Older Sands Ten Mile Hill (Liquefied)

  18. Age Scaling Factors for Penetration – VS Equations SPT-VS data CPT-VS data 100 102 104 106 108 Age, years

  19. Age Correction Factors

  20. Conclusions • For the compiled Holocene data, the VS-based CRR curve by Andrus and Stokoe is on average more conservative than the SPT- and CPT-based curves. • Values of VS from liquefied sands are lower than those from non-liquefied sands with similar penetration resistances. • The penetration-VS equations developed for Holocene sands change by a factor of about 0.073 per log cycle of time, based on data from non-liquefied sands. • The VS-based CRR curve is characterized for soils with age of roughly 10 years; and new age scaling factors are proposed.

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