A New Free-Free Resonant Column Device for Measurement of G_max and D_min at Higher Confining Stresses
Kalinski, ME
Department of Civil Engineering, University of Kentucky, Lexington, KY

R. Thummaluru, MS
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 (s¢_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 (G_max) and small-strain material damping (D_min). However, s¢_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 s¢_o greater than 80 kPa, while remotely exciting the specimen with a rotary solenoid. Test results demonstrate its potential for measuring G_max and D_min under higher levels of s¢_o that are more representative of in situ conditions.

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

Paper ID: GTJ12187
DOI: 10.1520/GTJ12187

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Author Kalinski, ME Affiliation Department of Civil Engineering, University of Kentucky, Lexington, KY Author R. Thummaluru, MS Affiliation Alexcom and Associates, Fredricksburg, VA Author Kalinski ME, R. Thummaluru MS Title A New Free-Free Resonant Column Device for Measurement of G_max and D_min at Higher Confining Stresses Symposium , Committee: on