海冰弯曲强度及其破坏过程的试验研究  

Experimental study on the flexural strength and failure process of sea ice

作　　者：孟丁丁 陈晓东[1] 季顺迎[1] MENG Dingding;CHEN Xiaodong;JI Shunying(State Key Laboratory of Structure Analysis of Industrial Equipment,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学工业装备结构分析国家重点实验室,辽宁大连116024

出　　处：《海洋通报》2021年第6期609-620,共12页Marine Science Bulletin

基　　金：国家重点研发计划重点专项(2017YFE0111400;2016YFC1401505);国家自然科学基金(51639004;41576179)。

摘　　要：为确定海冰温度、卤水体积等因素对海冰弯曲强度的影响,本文对辽东湾东岸海域的平整冰进行了现场取样,并在试验机压头加载速率为0.1 mm/s的情况下进行了三点弯曲试验。试验结果表明,海冰试样在-35~-5℃温度范围内呈现出三种不同的破坏模式,主要表现为海冰弯曲断裂时裂纹形状的差异。当温度在-15~-10℃之间时,海冰试样多表现为断裂面粗糙的韧性破坏模式,部分试样在主裂纹扩展过程中伴随有次生裂纹的衍生;当温度低于-15℃时,海冰试样多表现为脆性破坏,具有一条由下至上的完整光滑断裂面;而二次破坏的温度与脆性破坏、韧性破坏的温度均有交叉,分布于-20~-5℃之间,试验结果呈现上部粗糙下部光滑的断裂面。对海冰的应力分析表明,不同破坏模式下的弯曲强度值呈阶梯分布,海冰发生脆性破坏时的弯曲强度要高于其他两种破坏模式,发生韧性破坏时的弯曲强度最小。在不同断裂模式下,海冰的弯曲应力达到最大值后的下降趋势有明显差异,韧性断裂时弯曲应力下降缓慢,脆性破坏时则突然下降为0,而二次破坏应力突然下降后仍以较小的值缓慢下降至接近于0。最后,本文还讨论了海冰弯曲强度与卤水体积的对应关系,结果与其他相关文献具有很好的一致性。以上研究有助于更好地理解海冰的力学性质,为极地船舶与海洋工程结构抗冰设计提供参考依据。To determine the influence of sea ice temperature,brine volume and other factors on the bending strength of sea ice.In this study,the field sampling of level ice in the east coast of Liaodong Bay was carried out,and the three-point bending tests of sea ice were performed under the pressure head of testing machine loading rate of 0.1 mm/s.The experimental results show the three different failure modes of sea ice samples in the temperature range of-35~-5℃,mainly reflected by the dif-ferent crack shapes of sea ice.When the temperature is between-15℃and-10℃,most of the sea ice samples present duc-tile failure mode with rough fracture surface,and some samples have secondary crack accompanying the main crack propaga-tion.When the temperature is lower than-15℃,most of the sea ice samples are in brittle failure mode with a complete fracture surface from bottom to top.However,the temperature of secondary failure intersected with that of brittle and ductile fail-ure,which distributed between-20℃and-5℃,and the fracture surface presents rough at the top while smooth at the bot-tom.From the flexural stress of sea ice samples,we can also find that the bending strength under different failure modes has obvious ladder distribution.The flexural strength of sea ice under brittle failure is higher than the other two modes of destruc-tion,the bending strength is the smallest when ductile failure occurs.The stress evaluation processes of sea ice are also differ-ent obviously.The bending stress decreases slowly in ductile fracture,and suddenly drops to 0 in brittle failure,while the sec-ondary failure stress still keeps decreasing slowly to close to 0 after the sudden decrease.Finally,the relationship between the flexural strength of sea ice and the brine volume was discussed.These studies are helpful to understand the mechanical prop-erties of sea ice,providing reference for the anti-ice structure design of polar ship and offshore structures.

关 键 词：海冰 弯曲强度 破坏模式 韧脆特性 现场试验 

分 类 号：P731.15[天文地球—海洋科学]