Carbon dioxide (CO₂) storage in deep saline aquifers has been lauded as one of the most effective techniques to mitigate greenhouse effects globally. Nevertheless, despite many investigations, clarifying the influence of CO₂–water–rock interactions on the fracture characteristics of sandstone remains a challenge. In this work, the fracture properties of sandstone collected from the Triassic Xujiahe Formation are systematically studied in tests simulating CO₂ sequestration. The results indicate that the water–rock interactions occur in a system of sandstone and CO₂ solution. Due to the interactions, the porosity of sandstone specimens slightly increases from 8.24 to 8.45% when immersed in CO₂ solution and from 8.20 to 8.40% in pure water after 28 days. In addition, the parameters of fracture toughness, tensile strength, uniaxial compressive strength and elastic modulus are reduced by 24.12%, 27.16%, 31.78% and 33.21% after immersion in pure water, while they are reduced by 24.05%, 29.72%, 30.75% and 25.79% after immersion in CO₂ solution, respectively. These results suggest that the mechanical properties of the Xujiahe sandstone deteriorate after soaking. The results also show that the critical fracture energy of sandstone specimens after immersion in the CO₂ solution is 10.4% lower than that in pure water and 24.1% lower than that under natural drying conditions. These research results have great significance for understanding the dissolution processes during CO₂ sequestration and their influence on the fracture properties of sandstone, which may be theoretically instructive for CO₂ storage in the Xujiahe Formation in the Sichuan Basin.

深层盐水中的二氧化碳（CO ₂）储存已被誉为减轻全球温室效应的最有效技术之一。尽管如此，尽管进行了许多研究，但要弄清CO _2-水-岩相互作用对砂岩断裂特征的影响仍然是一个挑战。在这项工作中，在模拟CO ₂固存的试验中，系统地研究了从三叠纪须家河组采集的砂岩的断裂特性。结果表明，水-岩相互作用发生在砂岩和CO ₂溶液系统中。由于相互作用，当浸入CO _2中时，砂岩样品的孔隙度从8.24略微增加到8.45％28天后在纯水中溶解8.20至8.40％。此外，浸泡在纯水中后，断裂韧性，拉伸强度，单轴抗压强度和弹性模量的参数分别降低了24.12％，27.16％，31.78％和33.21％，而它们分别降低了24.5％，29.72％，30.75和23.5％。分别浸在CO ₂溶液中后的重量百分比和25.79％。这些结果表明，徐家河砂岩的机械性能在浸泡后会变差。结果还表明，在CO ₂溶液中浸泡后，砂岩样品的临界断裂能比纯水低10.4％，比自然干燥条件下低24.1％。这些研究结果对于理解CO过程中的溶解过程具有重要意义。₂固存及其对砂岩断裂特性的影响，从理论上对四川盆地须家河组CO _2的储藏具有指导意义。