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

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Presentation on theme: "Microzonation Study of Soil Liquefaction Potential and Damage Wei F. Lee Taiwan Construction Research Institute Ming-Hung Chen National Center for Research."— Presentation transcript:

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 Liquefaction microzonation in metropolitan Area Sensitivity- adequate analysis unitSensitivity- adequate analysis unit Population- building coveragePopulation- building coverage Foundation typeFoundation type GIS application GIS application

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

4 Procedure Geological Environmental Topography and Surface condition Level One Grid Generation ⅠⅡⅢ

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

6 Structure Coverage Rate Structure Coverage Rate Structure Coverage RateGrid Size Below 25 ﹪ 1600×1600 m2 25 ﹪ ~ 60 ﹪ 800×800 m 2 Above 60 ﹪ 400×400 m 2 Grid Setup

7 GIS Application GIS Combined Slope Management Database

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

9 Case Studied Level I assessment Level I assessment Kaohsiung CityKaohsiung City Level I, II and III, with initial hazard analysis Level I, II and III, with initial hazard analysis Taipei CityTaipei City Evaluation method Evaluation method Yuan Lin TownshipYuan 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 Grid Regular Method

19 Microzonation Grid Modified Method

20 Hydraulic Map and Administration

21 Taipei Basin First Class Evaluation

22 Second Class Evaluation 2002 Ground Water

23 Second Class Evaluation Geology

24 Third Class Evaluation SPT Boring Locations

25 Seed97 Liquefaction Potential Evaluation (Dry Season)

26 Dry Season Regular Regular Mocrozonation Wet Season Dry Season Modified Microzonation

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 Database including 279 cases 80% for training 20% for testing Yuan Lin Artificial Neural Network (ANN) Non-Liquefied cases 237 Liquefied cases 42

33 Selected Input Factors 1.Depth of liquefiable soil 2.SPT-N value 3.Fines Content (FC) 4.Total Stress 5.Effective Stress 6.D 50 7.Peak Horizontal Acceleration ( a max ) 8.Earthquake Magnitude ( Mw ) 9.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 Soil Properties Liquefaction Potential ANN-1 Model

36 ANN-1 model Input and Output Input Output

37 Data Normalizing

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

39 ANN-2 model Input and Output Input Output

40 ANN Results

41 Critical State

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

43 Thank You Questions


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