Temperature cycling and its effect on mechanical behaviours of high-porosity chalks

Abstract

Abstract Temperature history can have a significant effect on the strength of water-saturated chalk. In this study, hydrostatic stress cycles are applied to understand the mechanical response of chalk samples exposed to temperature cycling between each stress cycle, compared to the samples tested at a constant temperature. The total accumulated strain during a stress cycle and the irreversible strain are reported. Chalk samples from Kansas (USA) and Mons (Belgium), with different degrees of induration (i.e. amount of contact cementation), were used. The samples were saturated with equilibrated water (polar) and non-polar Isopar H oil to quantify water weakening. All samples tested during 10 stress cycles with varying temperature (i.e. temperature cycled in between each stress cycle) accumulated more strain than those tested at constant temperatures. All the stress cycles were performed at 30\xa0°C. The two chalk types behaved similarly when saturated with Isopar H oil, but differently when saturated with water. When saturated with water, the stronger Kansas chalk accumulated more total strain and more irreversible strain within each stress cycle than the weaker Mons chalk.