In this study, strength and deformation characteristics of rocks were examined at low temperatures. That is, results by the uniaxial tension test and the compression test were compared and discussed. It is supposed that an opening is excavated in a rock mountain to a depth of 100m beneath the ground surface with a diameter of 10m and LNG was stored there in. Using the results of the tests mentioned above, temperature and stress distribution around openings were analyzed. Then the thermal behavior of the rock mass around openings which was analyzed using the results of the uniaxial tension test and by the compression test was compared and discussed.
The authors have proposed and discussed storage of low temperature materials in openings excavated in rock mountains. The low temperature materials are LNG (−162 °C), LPG (−43 °C) and frozen food (−60 °C). This method has many advantages, such as efficient utilization of land, energy conservation, large scale storage, preservation of the environment, etc. In this case, as the rock mass around the openings will receive effects of low temperatures, it is necessary to consider the thermal behavior and the stability of openings. In this study, strength and deformation characteristics of rocks were examined at low temperatures. That is, results by the uniaxial tension test and the compression test were compared and discussed. It is supposed that an opening is excavated in a rock mountain to a depth of 100m beneath the ground surface with a diameter of 10m and LNG was stored within by using a "water curtain system". Using the results of the tests mentioned above, temperature and stress distribution around openings were analyzed by Finite Divided Element Method (FDEM) (Inada & Shigenobu 1983) and Crack Analysis Method (CAM) (Inada & Taniguchi 1987). Then the thermal behavior of the rock mass around openings which was analyzed using the results of the uniaxial tension test and the compression test, was compared and discussed.
The rocks used for the tests were granite, andesite and sandstone. In general, granite has many microcracks which exist parallel to three planes perpendicularly intersecting each other, and the plane which has the largest number of microcracks is called the "rift plane", the second is the "grain plane" the third is the "hard way plane" (Fleischmann 1990). In this study, in agreement with this classification, these planes were determined by measuring elastic wave propagation velocity of the block of rock. Specimens were formed 30 × 100 mm for the uniaxial tension test, 30 × 60 mm for the uniaxial compression test, and 30 × 30 mm for the Brazilian test. Specimens were prepared as "dry" by drying for one week in a desiccator, and as "wet" by being kept in a desiccator filled with distilled water for 5 hours using a vacuum pump. The physical properties of these specimens are shown in Table 1.
