CO₂ sequestration via gas hydrate method shows great potential on promoting global carbon cycling and reducing greenhouse effect through injecting CO₂ to hydrate reservoirs. However, the overconsolidation state induced by hydrate formation or interconversion of CO₂ and CH₄ hydrate would affect the stability of silty reservoirs after CO₂ sequestration, but currently, few studies have been presented on this topic. To this end, a sequence of overconsolidation and drained shear tests on CO₂ hydrate-bearing silty sediments (HBSSs) were carried out in this study to simulate and elucidate the effect of overconsolidation on the mechanical behaviours of CO₂ HBSSs. The results reveal that all HBSSs with different hydrate saturations exhibit strain hardening and shear contraction behaviours with or without overconsolidation, while an increase in the overconsolidation ratio (OCR) enhances the deviator stress and alleviates the contraction effect. In addition, a strengthening effect on the stiffness, strength and resistance of deformation of HBSSs is induced by overconsolidation, while this effect becomes more prominent as the hydrate saturation increases. HBSSs with higher OCRs and hydrate saturations generally have lower stress-dilatancy ratios. Moreover, the shear paths of HBSSs with higher OCRs deviate farther from the normal consolidation line of hydrate-free silty sediments. This study is expected to provide theoretical guidance for the CO₂ sequestration via gas hydrate in silty reservoirs.

天然气水合物法封存CO _2通过向水合物储层注入CO ₂在促进全球碳循环和减少温室效应方面显示出巨大潜力。然而， CO 2 水合物形成或CO ₂与CH _4水合物相互转化引起的超固结状态_{会影响CO 2}封存后粉质储层的稳定性，但目前关于该主题的研究较少。为此，本研究对含CO ₂水合物的粉质沉积物（HBSSs）进行了一系列超固结和排水剪切试验，以模拟和阐明超固结对CO力学行为的影响。_2个HBSS。结果表明，所有水合物饱和度不同的HBSS在有或没有超固结的情况下都表现出应变硬化和剪切收缩行为，而超固结率（OCR）的增加会增强偏应力并减轻收缩效应。此外，强化效果超固结对 HBSSs 的刚度、强度和变形阻力的影响是由超固结引起的，而随着水合物饱和度的增加，这种影响变得更加突出。具有较高 OCR 和水合物饱和度的 HBSS 通常具有较低的应力-剪胀比。此外，具有较高 OCR 的 HBSS 的剪切路径偏离无水合物粉质沉积物的正常固结线更远。该研究有望为粉砂质储层通过天然气水合物封存_{CO 2}提供理论指导。