Experimental quantification of anisotropy in fabric

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Waves are an engineer’s best friends or the worst enemies

The purpose of this study is to develop and verify an indirect measure of coarse-grained soil fabric using shear wave velocities ($V_s$) for materials with different particle shapes. $V_s$ is obtained by a novel multi-bender element system which consists of five pairs of bender elements, with each pair capturing the shear wave velocity in a specific orientation along the specimen.

The initial planning of this project consisted of; a) selection of a suitable test setup, b) design and fabrication of end caps, c) various electrical connections for bender elements, waveform generator, and the oscilloscope, d) selection of test materials. Based on DEM results, the orientation of bender elements was selected. Mono sized glass beads, prolate rice particle and Monterey sands were selected as the test materials providing a range of particle shapes. The test results indicate that the particle shape, arrangement, and contact behavior has a considerable effect on the stiffness anisotropy, which manifests in the directional variation of V s . The results indicate two extreme ends in the variation of $V_s$ for granular materials, one end being the perfect spherical shape and the other end being an elongated prolate shape.

This newly proposed test setup provides a complete angular distribution of fabric, which can be linked to the continuum mechanics framework and ultimately incorporated in the design and analysis of geotechnical systems.

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Mandeep Singh Basson
Graduate Student Researcher

My research interests include granular materials mechanics, fundamental soil mechanics and scientific computing.