ISSN: 0149-6115
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,KY,

Thummaluru, MSR
Geotechnical Engineer,Alexcom and Associates,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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