A comparison of short-circuited streaming potentials in Westerly granite from changes in the rock's volume, shape, saturation, and fracture under unconfined uniaxial compression

Abstract

An experiment was designed to gain some insight into the phenomena of electrical charge in the uniaxially stressed environment of a sample of Westerly granite. Varying properties of size, shape, saturation, and stress rate of the Westerly granite, a tentative set of physical relationships were measured. For instance, there is a strong suggestion that the amount of acoustic energy released when the sample fractures is proportionately related to the amount of charge that moves into or out of the sample, the net charge, over the period of the experiment. Increasing the concentration of the saturating solution increased the amount of charge that moved into or out of the sample. With all the samples that were dry, more charge move in than out over the period of the experiment. The few samples that were alike in every way before and after they fractured had a difference in charge and acoustic energy by a magnitude of their measured net charge and acoustic energy.