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U.S. – Taiwan Workshop on Soil Liquefaction November 4, 2003 Physical and Numerical Modeling Breakout Session.

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Presentation on theme: "U.S. – Taiwan Workshop on Soil Liquefaction November 4, 2003 Physical and Numerical Modeling Breakout Session."— Presentation transcript:

1 U.S. – Taiwan Workshop on Soil Liquefaction November 4, 2003 Physical and Numerical Modeling Breakout Session

2 Objectives: Identify research needs Identify collaborative opportunities

3 Physical Modeling Centrifuge Shaking table Field tests Numerical Modeling Constitutive models Boundary value problems Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … NEES

4 Physical Modeling Centrifuge Shaking table Field tests Numerical Modeling Constitutive models Boundary value problems Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others …

5 Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … Can measure V s pretty well in model tests Can we simulate SPT, CPT in model tests? Can we examine issue of small strain vs large strain behavior (w/r/t V s approach) in model tests? Can measure V s pretty well in model tests Can we simulate SPT, CPT in model tests? Can we examine issue of small strain vs large strain behavior (w/r/t V s approach) in model tests?

6 Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … Effects of fines have been studied in element tests Should test effects of fines on boundary value problems using model tests How do we prepare samples with fines or with gravel? Effects of fines have been studied in element tests Should test effects of fines on boundary value problems using model tests How do we prepare samples with fines or with gravel?

7 Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … Should create flow slides in models – instrument carefully to identify failure mechanism(s) How do we characterize soil in models – SPT? CPT? V s ? D r ? Other? Should create more realistic impermeable boundaries within slopes Should explore numerical models with improved large-strain capabilities, capabilities for near-zero effective stress Should model phenomena that influence case history backcalculation – mixing, hydroplaning, … Should create flow slides in models – instrument carefully to identify failure mechanism(s) How do we characterize soil in models – SPT? CPT? V s ? D r ? Other? Should create more realistic impermeable boundaries within slopes Should explore numerical models with improved large-strain capabilities, capabilities for near-zero effective stress Should model phenomena that influence case history backcalculation – mixing, hydroplaning, …

8 Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … Identification of appropriate ground motion parameters – energy-based? Peak amplitude-based? New parameters? Phasing of ground motions – more advanced characterization Identification of frequency bands in which high energy components exist. Wavelet and other higher level characterization techniques? Identification of appropriate ground motion parameters – energy-based? Peak amplitude-based? New parameters? Phasing of ground motions – more advanced characterization Identification of frequency bands in which high energy components exist. Wavelet and other higher level characterization techniques?

9 Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … Soil improvement Practitioners want guidance on mitigation methods Required degree of improvement Required geometric extent of improvement 3-D analytical procedures Soil improvement Practitioners want guidance on mitigation methods Required degree of improvement Required geometric extent of improvement 3-D analytical procedures

10 Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … Soil fabric Fabric shows significant effect in element tests; what about in model tests? Can we build models with fabric equivalent to that in field? How do we interpret model test results if fabric doesn’t match that in field? Soil fabric Fabric shows significant effect in element tests; what about in model tests? Can we build models with fabric equivalent to that in field? How do we interpret model test results if fabric doesn’t match that in field?

11 Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … Soil-Structure Interaction Kinematic demands on foundations Effects on retaining structures, waterfront structures, … Soil-Structure Interaction Kinematic demands on foundations Effects on retaining structures, waterfront structures, …

12 Issues SPT vs CPT vs V s Effects of fines Effects of gravels Residual strength Characterization of loading Others … International collaboration Yes How do we make it happen? Role of organizations – NSF, USUCGER Role of individuals International collaboration Yes How do we make it happen? Role of organizations – NSF, USUCGER Role of individuals


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