Selecting an appropriate shear plate configuration to measure elastic wave velocities
File(s)
Accepted version
Accepted version
Author(s)
Otsubo, Masahide
O’Sullivan, Catherine
Ackerley, Steven
Parker, Duncan
Type
Journal Article
Abstract
The (small-strain) elastic moduli of soil can be determined from stress wave velocity measurements. Bender/extender elements are widely used in laboratory experiments; however, discussion on how to accurately determine wave velocities using this method continues. Planar piezoelectric transducers (sometimes called shear plates) are a relatively new technology, whose use is not yet widely established, that appear to offer some advantages in comparison with bender/extender elements for laboratory geophysics tests. This contribution critically assesses the use of planar piezoelectric elements experimentally and using discrete element method (DEM) simulations. Planar piezoelectric elements capable of generating and receiving either shear or compression waves were placed in the top and base caps of a triaxial apparatus. Samples of glass ballotini were used so that stress wave propagation simulations could be performed on equivalent virtual samples using DEM. The appropriate shear plate configuration to effectively measure the shear wave velocity is explored. Considering both time- and frequency-domain responses, it is revealed that shear plate signals are sensitive to the surface area and thickness of the piezoelectric elements and to the lateral boundary conditions. Using a shear plate with the widest possible surface area exposed to the soil specimen is recommended to increase the signal-to-noise ratio and to produce more planar shear waves, resulting in a more accurate measurement of shear wave velocity.
Date Issued
2020-11-01
Date Acceptance
2019-10-07
Citation
Geotechnical Testing Journal, 2020, 43 (6)
ISSN
0149-6115
Publisher
ASTM International
Journal / Book Title
Geotechnical Testing Journal
Volume
43
Issue
6
Replaces
10044/1/78016
Copyright Statement
© 2019 ASTM. All Rights Reserved. ASTM International.
Identifier
https://www.astm.org/DIGITAL_LIBRARY/JOURNALS/GEOTECH/PAGES/GTJ20180146.htm
Subjects
Science & Technology
Technology
Physical Sciences
Engineering, Geological
Geosciences, Multidisciplinary
Engineering
Geology
dynamics
elasticity
waves
laboratory
shear plates
discrete element method
STIFFNESS
ELEMENT
TESTS
0905 Civil Engineering
Geological & Geomatics Engineering
Publication Status
Published
Date Publish Online
2019-12-26