U.S. Taiwan Workshop on Soil Liquefaction

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U.S. Taiwan Workshop on Soil Liquefaction Novemb
er 4, 2003 Physical and Numerical
Modeling Breakout Session
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Objectives Identify research needs Identify
collaborative opportunities
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Physical Modeling Centrifuge Shaking table Field
tests
Numerical Modeling Constitutive models Boundary
value problems
NEES
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Physical Modeling Centrifuge Shaking table Field
tests
Numerical Modeling Constitutive models Boundary
value problems
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Issues SPT vs CPT vs Vs Effects of fines Effects
of gravels Residual strength Characterization of
loading Others
Can measure Vs 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 Vs approach) in model tests?
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Issues SPT vs CPT vs Vs 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?
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Issues SPT vs CPT vs Vs 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? Vs?
Dr? 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,
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Issues SPT vs CPT vs Vs 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?
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Issues SPT vs CPT vs Vs 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
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Issues SPT vs CPT vs Vs 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 doesnt match that in field?
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Issues SPT vs CPT vs Vs 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,
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Issues SPT vs CPT vs Vs 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