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Predicting Future Performance of Improved Soils from Today’s Test Data

Predicting Future Performance of Improved Soils from Today’s Test Data. David A. Saftner , Russell A. Green, & Roman D. Hryciw. Outline. Sand Aging Overview Field Testing Explosive Compaction NEES Vibroseis Testing Laboratory Testing Summary. 10. 15. 20. 5. 0. +4. +2. 0. -2.

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Predicting Future Performance of Improved Soils from Today’s Test Data

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  1. Predicting Future Performance of Improved Soils from Today’s Test Data David A. Saftner, Russell A. Green, & Roman D. Hryciw

  2. Outline • Sand Aging Overview • Field Testing • Explosive Compaction • NEES Vibroseis Testing • Laboratory Testing • Summary

  3. 10 15 20 5 0 +4 +2 0 -2 -4 -6 -8 -10 -12 -14 Sand Aging Overview Practical Application CPT qc (MPa) Minimum Allowable qc Level: mPD Pre-vibrocompaction Post-vibrocompaction (~2 weeks after) Post-vibrocompaction (~6 weeks after) (from Debats and Sims 1997)

  4. Sand Aging Overview Proposed Mechanisms: • Mechanical – micro-level particle rearrangement • Chemical – precipitation and cementation • Dissolution of bubbles – blast gas or air • Biological – microorganisms

  5. Sand Aging Overview Methods of dealing with aging: • Scheduling time to allow aging to occur • Site specific aging metrics based on test improvement projects • Several proposed relationships:

  6. Sand Aging Overview Methods of dealing with aging: • Schmertmannet al. (1986) • Based on observations of a dynamic compaction test site prior to main site improvement project

  7. Sand Aging Overview Methods of dealing with aging: • Mesri et al. (1990) (qc)R = tip resistance at a reference time after the end of primary consolidation t = time of aged tip resistance measurement tR = reference time following primary consolidation CD = parameter reflecting densification method C = secondary compression index Cc = compression index

  8. Sand Aging Overview Methods of dealing with aging: • Charlie et al. (1992) K = empirical constant based on the chart N = number of weeks since disturbance

  9. Sand Aging Overview Methods of dealing with aging: • Joshi et al. (1995) Pt, P1 = penetration resistance on tth and 1st day following disturbance, respectively t = aging period in days a, b = constants depending on environmental conditions with average values shown in the table above

  10. Field Testing Paleo-liquefaction features Vibroseis site Blast site

  11. Field Testing Paleo-liquefaction feature

  12. Field Testing Clay 1.5m Upper Liquefiable Layer Loose ~GWT Sand 3m 5m Dense Sand 10m Lower Liquefiable Layer Loose Gravelly Sand 14m

  13. Field Testing Cone Penetration Test Vision Cone Camera Accelerometer Friction Sleeve Pressure Transducer

  14. ExplosiveCompaction

  15. Explosive Compaction A’ CPTu SCPT DMT VisCPT A CPT Pre-Blast One Week One Month 2.5 Months 20’ 3.5 Months One Year

  16. Explosive Compaction View A-A’ Clay 6.1m (20’) 1.5m Loose ~GWT Sand 3m 5m 0.6m (22.5”) Dense Sand 10m 1.15m (45.9”) Loose Gravelly Sand 12m 0.1m (4.5”) 14m

  17. Explosive Compaction

  18. Explosive Compaction Tip resistance, q (MPa) c 0 5 10 15 20 25 30 35 40 0 Pre-Blast Range (7 tests) One Week Range (6 tests) 2 2.5 Month Range (3 tests) Upper Liquefiable Layer 4 6 8 Depth, z (m) 10 Lower Liquefiable Layer 12 14 16 18 20

  19. Explosive Compaction Tip resistance, q (MPa) c 0 2 4 6 8 10 12 14 1.5 One Week Range (6 tests) One Week Range (6 tests) 2.5 Month Range (3 tests) 2.5 Month Range (3 tests) 2 2.5 3 Depth, z (m) 3.5 4 4.5 5

  20. Explosive Compaction Tip resistance, q (MPa) c 0 2 4 6 8 10 1.5 2 2.5 3 Depth, z (m) 3.5 4 One Week Average (6 tests) 4.5 1 Month Average (3 tests) 2.5 Month Average (3 tests) 1 Year Average (3 tests) 5

  21. Explosive Compaction

  22. NEES Vibroseis

  23. NEES Vibroseis SCPT DMT VisCPT CPT 7.5’ Pre-Blast One Week One Month 9 Months

  24. NEES Vibroseis

  25. NEES Vibroseis Tip resistance, q (MPa) c 0 5 10 15 20 25 30 35 40 0 Post-shake range (3 tests) One month range (3 tests) 1 2 Upper Liquefiable Layer Upper Liquefiable Layer 3 4 Depth, z (m) Depth, z (m) 5 6 7 8 9 10

  26. NEES Vibroseis Tip resistance, q (MPa) c 0 5 10 15 20 25 30 35 40 0 Pre-shake average (4 tests) Post-shake average (3 tests) 1 One month average (3 tests) One year average (3 tests) 2 Upper Liquefiable Layer 3 4 Depth, z (m) 5 6 7 8 9 10

  27. Laboratory Testing

  28. Laboratory Testing

  29. Summary • Sand aging is important because of dependence on in-situ testing when developing QA metrics • Following explosive compaction, CPT qc and Vs showed time-dependent increases • Following vibroseis shaking, Vs showed slight time-dependent increases but little change to CPT qc

  30. Summary • Comparison of several field disturbance techniques and laboratory testing performed on the same site/soil is unique in aging literature • Synergistic laboratory/field components of this research will allow development of a metric that predicts future in-situ test results using today’s data

  31. Acknowledgements • EERI, FEMA, & NEHRP • NSF & NEES • Professors Jerry Lynch, Richard Woods & Kyle Rollins • Jan Pantolin & YongsubJung • Mulzer Crushed Stone, Inc • Spartan Specialties, Ltd

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