Measurement and correlation of acoustic emissions and pressure stimulated voltages in rock using an electric potential sensor

Abstract

Previous laboratory-based studies have demonstrated pressure stimulated currents and electromagnetic emissions in rock and cement mortar can be used to assess damage. There is some debate whether the current and electromagnetic emission measurement technologies used thus far are viable for field application. The results presented here provide evidence that electric potential sensors are a viable new technology for field monitoring of electrical emissions. Cylindrical specimens of rock were loaded at constant stress or strain rates until failure occurred; strain gauges, piezoelectric transducers and electric potential sensors were used to monitor the strain, acoustic emissions and pressure stimulated voltages. Pressure stimulated voltages were observed in the linear elastic and inelastic deformation regions of loading, suggesting that pressure stimulated voltages are associated with microcracking and macrocracking events. Electric potential sensors are potentially a cost effective and more advanced alternative to piezo transducers and geophones for structural health monitoring of rocks.