Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

This paper concerns prediction of liquefaction-induced large deformation of geotechnical structures that will play major roles in practice of seismic performance design. To do this prediction, it is essential to establish a mechanical model for liquefied sand in which effective stress is null or extremely low. Although past model tests suggested that liquefied sand behaves similar to viscous liquid, there is an opinion against it that pore water pressure distribution in embedded structures produces an apparent rate-dependent behavior. This opinion was examined precisely and quantitatively by analyzing a full-scale model test to find that the pore pressure theory cannot account for the observed behavior. Then the authors conducted a new type of triaxial tests in which the effective stress was made extremely low, similar to the situation in fully liquefied sand, by free falling of a test device in a vertical shaft, thus making the gravity be zero, and a rate-dependent nature of liquefied sand was observed. By using the observed behavior of liquefied sand, a viscous model was developed. This viscous model was made use of to evaluate the performance of different mitigation measures that were proposed for river levees and other embankments subjected to liquefaction problems.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fifth Conference

Publisher

Missouri University of Science and Technology

Publication Date

5-24-2010

Document Version

Final Version

Rights

© 2010 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 24th, 12:00 AM May 29th, 12:00 AM

Zero-Gravity Triaxial Shear Tests on Mechanical Properties of Liquefied Sand and Performance Assessment of Mitigations Against Large Ground Deformation

San Diego, California

This paper concerns prediction of liquefaction-induced large deformation of geotechnical structures that will play major roles in practice of seismic performance design. To do this prediction, it is essential to establish a mechanical model for liquefied sand in which effective stress is null or extremely low. Although past model tests suggested that liquefied sand behaves similar to viscous liquid, there is an opinion against it that pore water pressure distribution in embedded structures produces an apparent rate-dependent behavior. This opinion was examined precisely and quantitatively by analyzing a full-scale model test to find that the pore pressure theory cannot account for the observed behavior. Then the authors conducted a new type of triaxial tests in which the effective stress was made extremely low, similar to the situation in fully liquefied sand, by free falling of a test device in a vertical shaft, thus making the gravity be zero, and a rate-dependent nature of liquefied sand was observed. By using the observed behavior of liquefied sand, a viscous model was developed. This viscous model was made use of to evaluate the performance of different mitigation measures that were proposed for river levees and other embankments subjected to liquefaction problems.