EXPERIMENTAL STUDY ON THE THERMAL FATIGUE OF ROCKS.

Abstract

In this paper, measuring the changes of the physical and mechanical properties of rocks including apparent specific gravity, P-wave velocity, Young's modulus and uniaxial compressive strength, the thermal fatigue process of rocks is characterized for four kinds of rocks, namely, OGINO tuff, EMOCHI welded tuff, AKIYOSHI marble and INADA granite. The cylindrical specimens are suddenly submerged into water after being heated and the cycle is automatically repeated in the testing machine. The maximum temperature and the maximum cylces in the experiment are 600 degree C and 5**4, respectively. It was found that the main failure mechanism is different between the crystalline rock and the sedimentary rock. The failure of the former takes place by the thermal interaction between minerals and that of the latter by the transient thermal stresses. As the result, crystalline rocks collapse to be particles or powders and sedimentary rocks are fractured initiating regular thermal cracks.