The authors have proposed and discussed temporary storage of heated water in openings excavated in rock mountain from the viewpoints of multiple-utilization of land, environmental safeguards, energy conservation, etc. When used for heated-water storage, the rock mass around the openings will receive the effects of the heated water. In this study, for obtaining physical properties used for analysis of thermal behavior of rock mass around openings, the effect of the difference between Wet (the water-retaining condition) and Dry and physical properties on strength, deformation characteristics and thermal properties at high temperatures were examined using 5 kinds of rock (granite, andesite, sandstone, tuff and mudstone). In addition, a uniaxial compression creep test at high temperatures of the rock was also carried out, then compared with the creep property at room temperature. The calculation of various constants on the creep was tried using Burgers model. In outline, the results show the strength of Wet rock is smaller than that of Dry, and strength lowers with the rise in the temperature, the lowering proportion being larger in Wet. The elastic modulus of tuff and mudstone are smaller than those of granite, andesite and sandstone. In particular, the lowering proportion at high temperatures is also large in Wet. Thermal property can be considered almost constant for practical use, and the effect of the temperature is small. As the difference of Dry and Wet is large, it seems that the effect of pore water is large. Especially, the tendency is remarkable in tuff and mudstone in which porosity is large. Temperature influences the uniaxial compression creep property of rock.
The authors have been proposed and discussed temporary storage of high and low temperature materials in openings excavated in rock mountain. Here, high temperature materials means such as heated water which is produced by surplus heat from garbage burning plants, while low temperature materials means such as LNG, LPG, frozen food etc. In this case, as the storage quantity of heated water, LNG and LPG will change with these use continually, rock masses around openings to store these materials will receive effects of thermal hysteresis of high and low temperatures. Therefore, obtaining the strength and deformation characteristics of rock affected by the thermal hysteresis becomes important for discussing the stability of the openings. In this study, strength and deformation characteristics of granite and tuff were examined after undergoing thermal hysteresis of high and low temperatures. From the results, it was found that the decreasing ratio of strength and deformation of rocks decrease with the increasing number of thermal hysteresis, and it is supposed that the value will converge to a constant value.
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