The effects of water content, temperature and loading rate on strength and failure process of frozen rocks

•Strength and deformation of dry and wet rocks were examined at sub-zero temperature.•Effect of temperature and loading rate on strength of frozen rocks were clarified.•Failure process of frozen rocks was considered by deformation behaviors.•A mechanism of increase in fracture initiation stress due to pore ice was proposed.

The effects of water content, temperature and loading rate on the strength and failure process of rock at sub-zero temperatures were investigated and are presented in this paper. Over the range of temperatures studied there was little change observed in the properties of dry rock. The presence of water in the rock, however, resulted in a marked increase in rock strength and the fracture initiation stress. Rock strength increased with amount of water present and the rate of load application, with the effect being exacerbated at the colder temperatures. Interestingly, the changes in strength were not uniform as there was a greater rate of increase in the tensile strength of rock with temperature than compressive strength. It is postulated that these changes in mechanical properties may be explained in part by a reduction in the stress concentration within the interstitial spaces and cracks of the rock samples tested.