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UBC Theses and Dissertations

The application of piezoceramic bender elements to the laboratory measurement of elastic wave velocities Jarvis, Kevin Donald Gibson


The objective of this thesis is to evaluate bender elements as a source and receiver of elastic waves in cohesionless sand. The techniques used to build the benders that are detailed include the use of an impedance analyzer to monitor changes in the electrical and mechanical response. Placing the benders in a bucket of sand demonstrated the short compact nature of the bender waveform in both a shear and compressional wave orientation. An experiment in a non-homogeneous sandbox showed the change in shear waveform with separation of the elements. A Plexiglas cylinder with benders was used to measure changes in shear and compressional wave velocity as a function of confining pressure and the saturation with water and silicon oil. The effects of friction along the walls of the cylinder resulted in an unknown and irreproducible confining stress on the sand between the benders. An experiment to study the effect of silicon oil viscosity on shear modulus was inconclusive as a result of the unknown stress condition. The bender elements proved to be an excellent source and receiver of elastic waves in cohesionless sand.

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