Thermal diffusivity, the coefficient of thermal expansion and the velocity of ultrasonic waves which are necessary for calculation of thermal distribution and thermal stresses in a rock, were measured at low temperatures. Granite and Andesite were used as the rock samples. The measuring method of thermal diffusivity was developed in accordance with the application of Schmidt's theory.
The main results obtained are as follows:
(1) The thermal diffusivity of the wet rock specimens which have been submerged in water increased with lowering temperature, while that of the air dry specimens was nearly constant.
(2) The tangential coefficient of thermal expansion of the rocks decreased with lowering temperature.
(3) The dynamic Young's modulus calculated from the velocities of longitudinal and shear waves increased with lowering temperature.
