Theory and Techniques for Vibration-Induced Conductivity Fluctuation testing of Soils

TL;DR

This paper introduces a theoretical framework and new measurement techniques for vibration-induced conductivity fluctuations in soils, emphasizing compression vibrations and improved electrode configurations for more accurate testing.

Contribution

It presents a novel analysis of electromechanical responses and proposes new measurement schemes using compression vibrations and optimized electrode arrangements.

Findings

Compression vibrations produce sideband spectral lines shifted by vibration frequency.

Four-electrode measurements reduce electrode effects and measurement errors.

New measurement arrangements are suitable for both laboratory and field conditions.

Abstract

First we present and theoretically analyze the phenomenological physical picture behind Vibration-Induced Conductivity Fluctuations. We identify the relevant tensors characterizing the electromechanical response against the vibrations for both longitudinal and transversal responses. We analyze the conductivity response with acceleration type vibrations and a new scheme, measurements with more advantageous compression type vibrations that are first introduced here. Compression vibrations provide sideband spectral lines shifted by the frequency of the vibration instead of its second harmonics; moreover the application of this method is less problematic with loose electrodes. Concerning geometry and electrodes, the large measurement errors in earlier experiment indicated electrode effects which justify using four-electrode type measurements. We propose and analyze new arrangements for the longitudinal and transversal measurements with both compression vibration and acceleration vibration for laboratory and field conditions.