A New Testing Method for the Characterization of the Tension-Compression Cyclic Behavior of Rock Salt

Abstract

To improve the stability of salt cavern gas storage, the tension-compression cyclic behavior of surrounding rock must be correctly characterized. This article proposes a new tension-compression cyclic testing method in which a rock specimen–fixing device with position-limit spring components is provided. The fixing device can both bear compressive stress and direct tensile stress, that is, the new testing method implements a completely reversed stress condition: direct tensile stress and compressive stress. Investigations on the tension-compression cyclic behavior of pure rock salt and impure rock salt were undertaken using this method. In the experiment, four cycles of tension-compression alternation loading were carried out first, then a tensile stress was applied until the occurrence of rock failure. The axial stress-strain curve of pure rock salt shows hysteretic behavior within each cycle. The damage evolution process induced by the tension-compression cyclic stress was illustrated by the spatial distribution of acoustic emission (AE) events and the variation of AE cumulative counts. The experimental results indicate that the developed method can be easily applied to investigate the tension-compression cyclic behavior of rock material.