Location

San Diego, California

Session Start Date

3-26-2001

Session End Date

3-31-2001

Abstract

A series of undrained cyclic torsional shear tests was conducted to investigate the effects of initial confining stress level on liquefaction resistance of sand. Hollow-cylindrical dense specimens with outer diameter of 10 cm, inner diameter of 6 cm and height of 20 cm are prepared with two kinds of sand. After being saturated, they were isotropically consolidated under an initial confining stress σc’ of 4.9, 9.8 or 98 kPa, and subjected to undrained cyclic torsional shear while maintaining the axial and lateral stresses constant. The amplitude of the cyclic torsional shear stress τcy was kept constant with a correction for the effects of membrane force. As a result, for both sands, the cyclic shear stress ratio τcy/ σc’ to cause liquefaction in a specified number of cycles was found to increase as the initial confining stress σc’ decreased. This tendency is consistent with the results of previous studies based on undrained cyclic triaxial tests. Such increase in the liquefaction resistance under low confining stress levels should be considered in analyzing relevant model test results. It was also demonstrated that in conducting cyclic torsional shear tests under low confining stresses, correction for the effects of membrane force is indispensable.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

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

Meeting Name

Fourth Conference

Publisher

University of Missouri--Rolla

Publication Date

3-26-2001

Document Version

Final Version

Rights

© 2001 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Mar 26th, 12:00 AM Mar 31st, 12:00 AM

Cyclic Torsional Shear Tests on Liquefaction Resistance of Sands Under Low Confining Stress

San Diego, California

A series of undrained cyclic torsional shear tests was conducted to investigate the effects of initial confining stress level on liquefaction resistance of sand. Hollow-cylindrical dense specimens with outer diameter of 10 cm, inner diameter of 6 cm and height of 20 cm are prepared with two kinds of sand. After being saturated, they were isotropically consolidated under an initial confining stress σc’ of 4.9, 9.8 or 98 kPa, and subjected to undrained cyclic torsional shear while maintaining the axial and lateral stresses constant. The amplitude of the cyclic torsional shear stress τcy was kept constant with a correction for the effects of membrane force. As a result, for both sands, the cyclic shear stress ratio τcy/ σc’ to cause liquefaction in a specified number of cycles was found to increase as the initial confining stress σc’ decreased. This tendency is consistent with the results of previous studies based on undrained cyclic triaxial tests. Such increase in the liquefaction resistance under low confining stress levels should be considered in analyzing relevant model test results. It was also demonstrated that in conducting cyclic torsional shear tests under low confining stresses, correction for the effects of membrane force is indispensable.