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.海洋与湖冰覆盖体对气候变化引发的各类威胁（如冰范围缩减、热裂缝（thermal cracking）增多）的脆弱性，亟需开展全面系统的调查研究。本实验于2022至2024年间在达特茅斯学院冰研究实验室完成，通过液氮对实验室培育的淡水冰与天然一年期海冰施加热冲击（thermal shock），冲击方式分为两类：仅作用于冰样的窄带区域，或覆盖整个冰样表面。本研究探讨了热裂缝对冰抗弯强度（flexural strength）的影响。实验结果显示，两类冰在热冲击后初始阶段均出现强度下降；当仅窄区域受冲击时，冰的强度可完全恢复；而淡水冰仅在全表面受冲击时仅能实现部分恢复，海冰则可完全恢复，二者行为差异显著。反复的裂缝形成与愈合循环不会对抗弯强度的恢复产生影响。此外，蠕变（creep）实验揭示了压应力对冰愈合过程的调控作用，阐明了其在冰烧结（sintering）与强度恢复中的关键机制。在1MPa压应力下作用1小时可显著提升强度恢复效果，抗弯强度几乎完全复原。窄区域与全表面受冲击的行为差异，可归因于窄区域受冲击后愈合阶段形成的残余压应力（residual compressive stress）。海冰展现出更快的愈合速率，这可能源于其多孔结构与内部卤水（brine）的存在。本数据集包含以下五类数据：窄区域受热冲击后的开裂淡水冰抗弯强度、全表面受热冲击后的开裂淡水冰抗弯强度、全表面受热冲击后的开裂海冰抗弯强度、经5次冲击-愈合循环后的热开裂淡水冰抗弯强度，以及在1MPa压力下蠕变1小时的实验室培育淡水冰抗弯强度。