Influence of prefabricated fissure angle on sandstone damage and infrared radiation temperature characteristics

To study the influence of sandstone fissure angle on its characteristics, we performed sandstone uniaxial compression experiments with different prefabricated fissure angles. The infrared radiation temperature (IRT) response characteristics of the prefabricated fissure sandstone and the influences of the fissure angles on mechanical properties, failure modes and infrared radiation indicated the following: (1) the peak stress and failure rate increased as the prefabricated fissure angle increased; the stress peak σf had a quadratic functional relationship with the prefabricated fissure angle α, and the elastic modulus E was linearly related to the angle of the prefabricated fissure. (2) When 0° ≤ α < 45°, the prefabricated fissure tip formed wing cracks that were nearly perpendicular to the prefabricated fissure. When 45° ≤ α < 75°, the prefabricated fissure tip formed wing cracks that were nearly parallel to the prefabricated fissure, and the sample exhibited a local avalanche phenomenon. When α = 90°, the prefabricated fissure sample cracked in the stress direction. (3) The IRT curve exhibited different stages in the loading process. The change of the IRT curve was consistent with the changes in the load curve, which can accurately predict sandstone failure. The IRT curve varied as the angle changed. The IRT first increased and then decreased as the fissure angle increased, and the sample experienced the largest change in IRT at 60°.