Experimental and nonlinear constitutive damage model for sandstones after high-temperature treatment

Understanding the changes in rock engineering properties after heating is vital, as high underground temperatures have contributed to disasters. Therefore, this study investigated the engineering properties of sandstone after high-temperature treatment to understand the thermo-mechanical behavior of these sandstones for long-term underground mine and tunneling safety and maintenance. Investigating the strength, damage, and failure characteristics of rock under unconfined compressive testing, X-ray diffraction, and scanning electron microscopy is crucial to mitigating underground rock hazards. The results show that temperature played a significant role in the evolution of compressive strength, deformation modulus, and damage variable in the sandstones. The peak strength of the sandstones decreases with increasing temperature, while the damage variables increase. In addition, based on Lemaître’s strain equivalence principle, a nonlinear constitutive model for sandstone was developed for high-temperature conditions. Results obtained under different high-temperature conditions were used to validate the model. The proposed model shows excellent agreement with the experimental results across all temperatures ( R 2 > 0.998) and outperforms selected existing models in fitting the present dataset.