Microcracking of salt under creep

Abstract

During creep in rock salt samples, the concentration of microcracks decreases, due to their amalgamation and formation of larger cracks at rates proportional to the load. Moreover, the increase in the number of cracks, according to the acoustic emission and the electromagnetic radiation data, is the result of the formation of sub-micron cracks, which were undetected because of inadequate sensitivity and resolution of the microanalyzer. The parameters of the superimposed microcracking varied proportionally with the load and the duration of the tests. After 35 days under loads of 0.5 σc and 0.7 σc, the average crack length had increased by 29% and 50%. After 45 days, the increases were 42% and 54% (Fig 1). The average widths of the open cracks increased in the first case by 19% and 25%, and in the second, by 27% and 38%. The results can be used to evaluate the change in the void volume with time, as a result of expansion in rock salt deposits.