One of the problems of underground storage of L.N.G. is a rock stability at low temperature or after having been at low temperature.
In this study, the physical and the mechanical properties of rocks which had been at low temperatures of 0, -40, -80, -120, and -160°C were investigated. The physical and mechanical tests were carried out at room temperature.
The main results obtained are as follows:
(1) Both the compressive and the tensile strength of these rocks are smaller than those which had not been at low temperatures.
(2) The microscopic observation revealed an increase of microcracks in Granite with decreasing temperature, as indicated by the test results of Young's modulus and Poisson's ratio.
(3) The results of the X-ray diffraction show that cracks seem to grow at the interface between Quartz and Biotite, or between Quartz and Albite in Granite and Andesite.
(4) The coefficient of thermal expansion changes with cooling temperature.
