FRACTURE CHARACTERISTICS OF SANDSTONE UNDER THERMAL EFFECTS

It is important to study the mechanical characteristics of rocks to meet the increasing demands of deep mining and nuclear waste disposal. This paper mainly studies the temperature effects on fracture toughness of sandstone sample with double notches through meso-experiments. The experiments indicate that the fracture toughness increases exponentially with the temperature increment from 25℃ to 150℃ while decreases exponentially with the temperature increment from 150℃ to 300℃, and therefore 150℃ is the critical temperature. This result differs from most macroscopic experimental results. The possible reasons, such as meso-scale, clay mineral and thermal cracking, are analyzed in detail.