Experimental study on the tensile fracture characteristics of dry sandstone at low temperatures: Mechanisms and phenomena

• Published in: Engineering failure analysis 2025-01, Vol.167, p.108998, Article 108998
• Main Authors: Zhou, Zilong, Chen, Cuigang, Cai, Xin, Wang, Chu, Fang, Zhengtao, Wang, Peiyu, Yuan, Jifeng
• Format: Article
• Language: English
• Subjects: Brazilian test; Fracture surface; Low temperature; Roughness; Tensile strength
• ISSN: 1350-6307
• DOI: 10.1016/j.engfailanal.2024.108998

•The microscopic mechanisms of tensile failure in dry rocks at low temperatures are revealed.•The effect of low temperature on the energy evolution of rocks is explored.•The effect of low temperature on the micro and macro morphology of rock fracture surfaces is determined. Some high-altitude open-pit mines experience periods of very low rainfall during the year, and the dry, frozen rock in the slope is susceptible to tensile damage. To investigate the effect of temperature on the tensile fracture characteristics of dry rocks, Brazilian tests were conducted on dry sandstones at various temperatures. Strain changes on the specimen surface were monitored using digital imaging correlation during the test. The fracture surface morphology was analyzed using a three-dimensional surface scanner and scanning electron microscope after specimen failure. The results indicate that the tensile strength, modulus of elasticity, and brittleness index of dry sandstones increase and then decrease as temperature drops, with the inflection point at −30 °C. The impact of low temperatures on the elastic phase is a key factor influencing the variation in tensile strength and energy rate. A clear linear relationship exists between the energy rate, the energy absorbed in the elastic stage, and the tensile strength at various low temperatures. Temperature changes influence the number of transgranular and intergranular cracks in a specimen during fracture, which subsequently alters the fracture surface roughness. The strengthening and weakening effects caused by mineral grain shrinkage together influence the tensile mechanical properties of low-temperature dried sandstone. Above −30 °C, the strengthening effect dominates, while below −30 °C, the weakening effect becomes more significant. These findings offer valuable insights for the design and construction of slope engineering in cold regions.