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Testing of Unknown Foundation: A Case Study with Comparison of Different NDT Methods

Testing of Unknown Foundation: A Case Study with Comparison of Different NDT Methods. Bill X. Yu Assistant Professor, Department of Civil Engineering, Case Western Reserve University, OH, USA, 216-368-6247, xxy21@case.edu. Present at Ohio Transportation Engineering Conference

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Testing of Unknown Foundation: A Case Study with Comparison of Different NDT Methods

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  1. Testing of Unknown Foundation: A Case Study with Comparison of Different NDT Methods Bill X. Yu Assistant Professor, Department of Civil Engineering, Case Western Reserve University, OH, USA, 216-368-6247, xxy21@case.edu Present at Ohio Transportation Engineering Conference Oct 23-24, 2007

  2. Acknowledgements • Jian Fang, Josh Adams, Guoming Lin, WPC, Inc., 2201 Rowland Avenue, Savannah, GA  31404, 912-629-4000 • Bin Zhang, Case Western Reserve University

  3. Introduction • Project Background • St. Joseph hospital expansion

  4. NDT Testing Plan After WPC Inc. Report, 2006

  5. Impact Echo: Testing Schematic

  6. Impact Echo: On-site Photos

  7. Impact Echo: Examples of Analyzed Signals

  8. Parallel Seismic Testing • Schematic • Borehole • SCPT

  9. Parallel Seismic Test: Photo During Test

  10. Parallel Seismic Testing: Ground Conditions by SCPT

  11. Parallel Seismic Testing: Recorded Signal

  12. Parallel Seismic Testing: After Signal Processing

  13. Parallel Seismic Testing: Wave Train Determination

  14. Parallel Seismic Testing: Wave Train

  15. Parallel Seismic Testing: Wave Train Validation

  16. Parallel Seismic: Sensitivity Analyses

  17. Magnetometer Method: Principle

  18. Vertical motion 1 ft Magnetometer: Validation of Concept

  19. Vertical cyclic motion of rod Slow vertical motion of rod Magnetometer: Validation of Concept At distance of 1 ft

  20. Magnetometer: Validation of Concept

  21. Magnetometer: Validation of Concept

  22. Magnetometer Method: Recorded signal

  23. Magnetometer: Signal Analyses for Pile Length

  24. Design Recommendations Based on Testing Results 50 Ton

  25. Advantages and Pitfalls Impact Echo • Fast, easy • Challenge in signal interpretation • Influence of internal reflection (due to geometry, crack etc) • Signal attenuation with depth • Wave modes • Source of error: assumption of wave speed

  26. Advantages and Pitfalls (cont.) Parallel Seismic Method • Requires borehole • Less influenced by pile integrity • Requires careful signal interpretation • Wave trains • Inflection point

  27. Advantages and Pitfalls (cont.) Magnetometer Method • Fast, easy • Requires borehole • Can be influenced by soil strata

  28. Summary of Experience • Geophysical methods are important tools to supplement engineering decisions • Different testing methods can serve • Properly applied • Properly interpreted • Geotechnical complexity needs to be considered

  29. Thank you !

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