ISSN: 1945-7545
CODEN: GTJODJ
Published Online: 5 January 2005
Page Count: 8

A New Free-Free Resonant Column Device for Measurement of Gmax and Dmin at Higher Confining Stresses

Kalinski, ME
Assistant Professor, University of Kentucky, Lexington, KY

Thummaluru, MSR
Geotechnical Engineer, Alexcom and Associates, Fredricksburg, VA

(Received 8 August 2003; accepted 13 August 2004)

Abstract

The fixed-free resonant column device has traditionally been used to measure shear modulus in laboratory soil and rock specimens. It is a proven method that provides measurements over a range of shear strain and effective confining stress (σ′_o), but the test relies on a specialized system of coils and magnets. The free-free resonant column device is a simpler device that allows for measurement of small-strain shear modulus (Gmax) and small-strain material damping (Dmin). However, σ′_o in the free-free device has traditionally been limited to a maximum attainable vacuum pressure of around 80 kPa, because the test has not been configured in a pressurized cell. Therefore, a new free-free device was developed to allow measurements in a pressurized cell with σ′_o greater than 80 kPa, while remotely exciting the specimen with a rotary solenoid. Test results demonstrate its potential for measuring Gmax and Dmin under higher levels of σ′_o that are more representative of in situ conditions.

Keywords:
resonant column, small-strain shear modulus, soil dynamics, confining stress, shear wave velocity, small-strain material damping

Paper ID: GTJ12187
DOI: 10.1520/GTJ12187
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