The authors have proposed and discussed temporary storage of heated water in openings excavated in rock mountains. Heated water, produced by surplus heat from garbage burning plants, should be used for many purposes such as district heating, heated water supply, green houses, etc. In this case, the rock mass around openings will receive the affect of thermal hysteresis of high temperatures as the storage quantity of healed water continually changes according to its use. In this study, strength and deformation characteristics of some types of rocks were examined after receiving thermal hysteresis of high temperatures. The effects of the amount of thermal hysteresis, atmospheric temperature, porosity, etc, on strength and deformation characteristics of rocks were discussed. The results of the tests mentioned above were used for analyzing temperature and stress distribution around openings by using the Finite Divided Element Method and FEM. Then the effect of thermal hysteresis of high temperatures on thermal behavior of some types of rock mass around openings was discussed.
The authors have proposed and discussed temporary storage of heated water in openings excavated in rock mountains. Heated water, produced by surplus heat from garbage burning plants, should be used for many purposes such as district heating, heated water supply,green houses, etc. This method has the advantages of efficient utilization of land and energy, etc. In this case, the rock mass around openings will receive the affect of thermal hysteresis of high temperatures as the storage quantity of heated water continually changes according to its use. Therefore, it is necessary to obtain strength and deformation characteristics of rock after receiving thermal hysteresis of high temperatures to consider the thermal behavior of rock mass around openings and the stability of openings. In this study, strength and deformation characteristics of some types of rocks were examined after receiving thermal hysteresis of high temperatures. The effects of the amount of thermal hysteresis, atmospheric temperature, porosity, etc. on strength and deformation characteristics of rocks were discussed. The results of the tests mentioned above were used for analyzing temperature and stress distribution around openings by using the Finite Divided Element Method and FEM. Then the effect of thermal hysteresis of high temperatures on thermal behavior of some types of rock mass around openings was discussed.
Figure 1 shows compressive strength ratio (б/ б) which is the ratio of the compressive strength of rocks after receiving thermal hysteresis (б) to before receiving thermal hysteresis (б). It is found that the value decreases with the increasing number of thermal hysteresis in all cases. It is supposed that microcracks occurred in the rock due to differences of thermal expansion among rock-forming mineral grains when the rocks receive thermal hysteresis. However, it is found that the ratio of decreasing compressive strength decreases with the increasing number of thermal hysteresis and the values converge to a constant value. Figure 2 shows the relationship between the compressive strength ratio and the variance of temperature in thermal hysteresis.
