In-situ heating test in the sedimentary soft rock. Part 1. Thermo-mechanical property of the mudstone and improvement of strain and temperature measurement

In this study, in-situ heating test was conducted in an underground cavern for the purpose of the examination of mechanical property under high temperature of the soft rock, the improvement of strain measurement in in-situ rock under the changing temperature condition and the understanding of the behavior in in-situ rock under high temperature. The results of the laboratory tests reveal that the compressive strength and creep characteristics under confining pressure of mudston were not affected by the temperature, the Young's modulus and creep characteristics under unconfined condition of that slightly affected at the high temperature. On the other hand, we developed the strain measuring method and successfully measured the strain and the temperature in the sedimentary soft rock under high temperature. The measured temperature agreed with the temperature which was simulated by the thermo-hydro-mechanical coupled analysis. The measured strain was mainly caused by the thermal expansion. (author)