Effects of temperatures on strength and deformability of Tak granite

Strength of granite under elevated temperatures is an important parameter governing the long-term stability of waste disposal boreholes.  The objective of this study is to experimentally determine the effects of elevated temperatures on the compressive strengths and elasticity of Tak granite.  The rock strength and deformability are determined under various temperatures and confining pressures.  The confining stresses are maintained constant at 0, 3, 7, to 12 MPa using a polyaxial load frame.  The rectangular block specimens have nominal dimensions of 5×5×10 cm3.  The testing temperatures are varied from 273 to 773 Kelvin.  The results indicate that the granite strength and elasticity exponentially decrease as the temperature increases.  The distortional strain energy criterion is proposed to describe the rock strengths as a function of mean strain energy.  The criterion fits well to the test results.  The proposed strength criterion is useful to predict the strength and deformation of granite around waste disposal boreholes under elevated temperatures.