A micro–macro model evaluating thermal treatment temperature effect on compressive failure of brittle rocks

Thermal treatment temperature strongly influences the compressive fracture mechanical properties of brittle rocks with many microcracks. However, the correlation between thermal treatment temperature, microcrack variation, and macroscopic compressive fracture properties is rarely established. A micro–macro model is suggested to evaluate the influence of thermal treatment temperature on the quasi-static compressive fracture relating to microcrack damage in brittle rocks. This model consists of the strain-crack relation, the wing crack model, and the proposed temperature-dependent initial damage and fracture toughness equations. The temperature-dependent equations of initial damage and fracture toughness are determined by the experimental data. The relationship curves between stress and strain are drawn under different temperatures. The effects of the thermal treatment temperature on the compressive strength, crack initiation stress, peak axial strain, and elastic modulus are studied. Sensitivities of the confining pressure and the size, friction, and angle of initial crack on the thermal treatment temperature-dependent compressive strength and crack initiation stress are discussed. The study results have an important role in the estimation of the stability of artificial underground engineering and the disaster of natural geology.