Strain‐rate effects on the strength of debris‐laden glacier ice

Abstract

Knowledge of the rate at which ice deforms is a key issue for understanding ice mass dynamics. Although the mechanical behaviour of clean glacier ice is now relatively well understood, there are many aspects of the behaviour of ice with different physical and chemical characteristics that remain to be investigated. In this paper, we examine the effects of strain‐rate variations on the measured strength of debris‐laden ice samples recovered from the basal zone of Taylor Glacier, Antarctica, and compare them with the effects on clean ice from the same glacier. At temperatures relatively close to the melting point, debris‐laden ice strength is strongly related to strain‐rate, whereas clean ice strength is not. At colder temperatures, the strength of debris‐laden ice does not appear to be affected by strain rate. These results indicate that at higher strain rates, debris‐laden ice is weaker, implying a rate‐related strain softening. They also confirm earlier findings that the behaviour of the basal ice is strongly temperature dependent.

Keywords:

• glaciology
• ice rheology
• debris‐laden ice
• strain‐rate
• Antarctica