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Microzonation Study of Soil Liquefaction Potential and Damage

Microzonation Study of Soil Liquefaction Potential and Damage. Wei F. Lee Taiwan Construction Research Institute Ming-Hung Chen National Center for Research on Earthquake Engineering. Problems and Solutions. Liquefaction microzonation in metropolitan Area Sensitivity- adequate analysis unit

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Microzonation Study of Soil Liquefaction Potential and Damage

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  1. Microzonation Study of Soil Liquefaction Potential and Damage Wei F. Lee Taiwan Construction Research Institute Ming-Hung Chen National Center for Research on Earthquake Engineering

  2. Problems and Solutions • Liquefaction microzonation in metropolitan Area • Sensitivity- adequate analysis unit • Population- building coverage • Foundation type • GIS application

  3. Southwest Taiwan Liquefaction Potential Microzonation ISSMFE TC4，1993 Grade Data Based Historic data I Geology map Surface map Aerial photo II Subsurface condition Ground surveying III Geotechnical Investigation Zonation

  4. Procedure Level One Geological Environmental Topography and Surface condition Grid Generation Ⅰ Ⅱ Ⅲ

  5. Procedure Level Two Influence Factor Selection Data Collection Level Three In-Situ/ Lab soil Properties Liquefaction Potential Evaluation and Risk Analysis

  6. Structure Coverage Rate Grid Size Below 25﹪ 1600×1600 m2 25﹪~ 60﹪ 800×800 m2 Above 60﹪ 400×400 m2 Grid Setup • Structure Coverage Rate

  7. GIS Application GIS Combined Slope Management Database

  8. GIS Evaluation Digitalized models Topographic map Geological map Geological zonation Weighting system Strike and fault map Geophysics Info. Hydraulic system map River system Past event record categorization

  9. Case Studied • Level I assessment • Kaohsiung City • Level I, II and III, with initial hazard analysis • Taipei City • Evaluation method • Yuan Lin Township

  10. Kaohsiung City

  11. Kaohsiung Liquefaction Potential Microzonation Regular Grid

  12. Kaohsiung Liquefaction Potential Microzonation Modified grid

  13. Kaohsiung Liquefaction Potential Microzonation Level One- Regular grid

  14. Southwest Taiwan Liquefaction Potential Microzonation Level One- Modified grid

  15. Kaohsiung Liquefaction Potential Microzonation Third Level (Seed97)－ Regular Grid

  16. Kaohsiung Liquefaction Potential Microzonation Third Level (T&Y)- Modified Grid

  17. Taipei City

  18. Microzonation GridRegular Method

  19. Microzonation GridModified Method

  20. Hydraulic Map and Administration

  21. Taipei Basin First Class Evaluation

  22. Second Class Evaluation2002 Ground Water

  23. Second Class EvaluationGeology

  24. Third Class EvaluationSPT Boring Locations

  25. Seed97 Liquefaction Potential Evaluation (Dry Season)

  26. Dry SeasonRegular Dry SeasonModified Microzonation Regular Mocrozonation Wet Season

  27. Comparison of indirect interpretation and proposed method

  28. Settlement Evaluation, (Seed97 method, dry season, Regular Microzonation)

  29. Lateral Spreading Evaluation (Bartlett and Youd,EQ Source B, dry season, Regular Microzonation)

  30. Lateral Spreading Evaluation (Bartlett and Youd,EQ Source A, dry season, Regular Microzonation)

  31. Analysis Tool NNT Evaluation

  32. Yuan LinArtificial Neural Network (ANN) Database including 279 cases 80% for training 20% for testing • Liquefied cases 42 • Non-Liquefied cases 237

  33. Selected Input Factors • Depth of liquefiable soil • SPT-Nvalue • Fines Content (FC) • Total Stress • Effective Stress • D50 • Peak Horizontal Acceleration（amax） • Earthquake Magnitude（Mw） • Liquefaction Initiation Evaluation

  34. Artificial Neural Network • Hidden Level：2 • Note：10 moving note structure (Wu,1991) • Connection ：Fully Connection • Weighting（Wij）：Quickprop (Fahlman，1988）

  35. ANN-1 Model Soil Properties Liquefaction Potential

  36. Input Output ANN-1 model Input and Output

  37. Data Normalizing

  38. ANN-2 Model Soil Properties Critical State Cyclic Resistance Ratio (CRR)

  39. Input Output ANN-2 model Input and Output

  40. ANN Results

  41. Critical State

  42. Future Research • More boring? • Visualized Iwasaki method? • Soil maps at different depth • Geophysics Measurement • Analysis Tool • Metropolitan Geotech Database (MGD) • One more big one!

  43. Thank You Questions

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