Journal Published Online: 23 January 2023
Volume 46, Issue 2

A Multi-orientation System for Determining Angular Distributions of Shear Wave Velocity in Soil Specimens



Soils typically have anisotropic mechanical and hydraulic properties due to the micro-scale interactions between particles that are influenced by particle morphology and depositional processes that can lead to particular particle arrangements (i.e., fabric anisotropy) and by imposed loading conditions and history (i.e., stress anisotropy). Experimental assessment of the anisotropy of soil specimens is a challenging feat, typically accomplished using specialized geotechnical testing and imaging equipment. The anisotropy of soil specimens can also be assessed based on measured responses, such as the velocity of propagating shear waves. This paper presents the development of a system that enables the measurement of shear wave velocity (VS) along different orientations and polarization planes using seven pairs of piezoelectric bender elements (BEs) to obtain angular distributions of VS. Specimens of glass beads and angular natural sands were tested in isotropic and one-dimensional (1D) compression to demonstrate the results obtained with the multi-BE system. The experimental results indicate that the effects of fabric and stress anisotropy can be identified by the angular distributions of VS, as well as measurements obtained along different polarization planes (i.e., VS,HH, VS,HV, and VS,VH). The level of anisotropy in soil specimens can be quantified either in terms of ratios of shear wave velocities or of parameters used to fit the angular VS distribution. The results also show that the parameters describing the relationship between VS and mean effective stress depend on the orientation of the propagating wave. The proposed system may enable the nondestructive assessment of soil specimen anisotropy using conventional laboratory equipment, which would complement other sophisticated experimental methods such as X-ray computed tomography and particle-based numerical simulations.

Author Information

Basson, Mandeep Singh
Department of Civil and Environmental Engineering, University of California Davis, Davis, CA, USA
Martinez, Alejandro
Department of Civil and Environmental Engineering, University of California Davis, Davis, CA, USA
Pages: 23
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Stock #: GTJ20210277
ISSN: 0149-6115
DOI: 10.1520/GTJ20210277