The mechanical behaviour of frozen sand down to cryogenic temperatures

The paper describes the results of an extensive testing nrogram conducted on a dense artificially frozen sand to investigate its mechanical behaviour down to cryogenic temperatures. A companion paper is presented by the same authors at this conference on a similar testing program on a frozen natural clay. Destructive and non-destructive tests were undertaken from a temperature slightly below 0°C to -160°C, the latter corresponding to the liquefying temperature of natural gas. In the first category, the uniaxial and diametral compression tests were included. The strain rate dependence of the mechanical properties has been investigated over the approximate nominal strain rate range extending from 3 × 10 -5 sec -1 to 3 × 10 -3 sec -1 . Over the whole temperature range studied, the stress-strain behaviour of the frozen sand was determined. The second test category included the measurement of microseismic activity and thermal expansion caused by a uniform temperature change during a slow temperature decrease. These tests allowed to infer the microstructural changes experienced by the frozen sand down to cryogenic temperatures and to relate them to the macroscopic mechanical behaviour observed in the destructive tests.