Recovery of strength in locally versus globally thermally cracked freshwater ice produced in the laboratory and sea ice collected in the Beaufort Sea, 2022-2024

The vulnerability of ocean and lake ice covers to climate change-induced threats, such as decreased extent and increased thermal cracking, necessitates comprehensive investigation. Conducted at Dartmouth College's Ice Research Laboratory from 2022 to 2024, experiments introduced thermal shock to laboratory-grown freshwater ice and natural first-year sea ice using liquid nitrogen to either a narrow band or the entire surface of ice samples. This study explores the impact of thermal cracking on the flexural strength. Results indicate that while both types of ice initially experience strength reduction after thermal shock, full recovery occurs when a narrow region is shocked, whereas only partial recovery is observed when the entire surface is shocked in freshwater ice, contrasting with full recovery in sea ice. Repeated cycles of cracking and healing do not affect flexural strength recovery. Moreover, experiments involving creep reveal the influence of compressive stress on healing, highlighting its role in ice sintering and strength restoration. Application of a compressive stress of 1 MPa for 1 hour enhances strength recovery, with flexural strength almost completely restored. The disparity in behavior between cracking a narrow region versus the entire surface is attributed to residual compressive stresses during healing when a narrow region is shocked. Rapid healing in sea ice is observed, likely due to its porous structure and the presence of brine.This dataset contains the following data: Flexural strength of cracked freshwater ice when a narrow region cracked, Flexural strength of cracked freshwater ice when all surface is cracked, lexural strength of cracked sea ice when all surface is thermally shocked, Flexural strength of thermally cracked freshwater ice after 5 cycles of shock/healing, Flexural strength of laboratory-grown freshwater ice that was crept for 1 hr at 1MPa.

海洋与湖冰盖对气候变化引发的威胁（如冰盖范围缩减、热裂缝增多）的脆弱性，亟需开展全面研究。本实验于2022至2024年间在达特茅斯学院（Dartmouth College）冰研究实验室开展，采用液氮对实验室培育的淡水冰与天然一年海冰的窄带区域或整个冰样表面施加热冲击。本研究探讨热裂缝对弯曲强度的影响。研究结果显示，两类冰在热冲击后初始强度均会下降；当仅对窄区域施加冲击时，淡水冰的强度可完全恢复，而当对整个表面施加冲击时，淡水冰仅能实现部分恢复——这与海冰可完全恢复的情况形成对比。反复的裂缝愈合循环不会影响弯曲强度的恢复。此外，蠕变实验揭示了压应力对冰愈合过程的影响，阐明了其在冰烧结与强度恢复中的作用。在1MPa压应力下持续1小时可强化强度恢复效果，弯曲强度几乎可完全复原。窄区域与全表面裂缝处理的行为差异，可归因于窄区域受冲击后愈合阶段存在的残余压应力。海冰展现出更快的愈合速度，这可能源于其多孔结构与卤水的存在。本数据集包含以下数据：窄区域开裂的淡水冰弯曲强度、全表面开裂的淡水冰弯曲强度、全表面受热冲击的开裂海冰弯曲强度、经过5次冲击/愈合循环的热裂淡水冰弯曲强度、在1MPa下蠕变1小时的实验室培育淡水冰弯曲强度。