基于CT观测的融化海冰孔隙结构特征研究  

Study on pore structure characteristics of sea ice based on CT observation

作　　者：王庆凯[1] 徐正宏 陈世杰 李志军[1] 卢鹏[1] Wang Qingkai;Xu Zhenghong;Chen Shijie;Li Zhijun;Lu Peng(State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,Dalian 116024,China;State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resource,Chinese Academy of Sciences,Lanzhou 730000,China)

机构地区：[1]大连理工大学海岸和近海工程国家重点实验室,辽宁大连116023 [2]中国科学院西北生态环境资源研究院冻土工程国家重点实验室,甘肃兰州730000

出　　处：《海洋学报》2024年第10期65-75,共11页

基　　金：国家自然科学基金(42276242,42320104004,52192692)。

摘　　要：孔隙结构是影响海冰力学性质的重要细观物理特征。为探究融化海冰的细观结构,在渤海盛冰期采集平整冰,并置于低温恒温环境(−1.0℃)内恒温48 h,进行CT扫描观测。确定气体−冰体−卤水的CT值阈值为−310 HU和−30 HU,对冰样CT图像进行三值化分割,识别气体和卤水孔隙,分析孔隙的二维形态特征;在此基础上进行冰样孔隙的三维重构,分析孔隙的三维形态特征。观测发现沿冰厚方向,冰样扫描断面气体面积分数为5.00%~35.93%,卤水分布不连续,面积分数最大为0.06%。气体和卤水孔隙平行冰面方向的截面形状近似圆形,圆度大于0.60。扫描断面内气体孔隙等效圆直径为1.1~3.2 mm,卤水孔隙等效圆直径为0.2~2.0 mm,且发现孔隙等效圆直径与面积分数呈正相关,与圆度呈负相关。三维结构上,根据孔隙球度(R_(sph))将气体孔隙分为4种典型形态:冠状孔隙(R_(sph)≤0.25)、不规则孔隙(0.25<R_(sph)≤0.45)、条状孔隙(0.45<R_(sph)≤0.60)和球形孔隙(0.60<R_(sph)≤1.00)。其中,冠状孔隙单体体积最大[平均体积(11522.8±5610.2)mm3]且数量最少,球形孔隙尺寸最小[平均直径(2.0±1.1)mm]且数量最多。卤水孔隙分为卤水通道(0.45<R_(sph)≤0.60)和卤水胞(0.60<R_(sph)≤1.00)。卤水通道平均长度(17.1±12.1)mm,卤水胞平均直径(1.5±0.9)mm;卤水通道数量较少,但体积占比与卤水胞相当。Pore structure is an important mesoscopic feature of sea ice affecting its mechanical properties.In order to investigate the mesoscopic structure of melting sea ice,a sea ice block was collected during severe ice period in the Bohai Sea.The ice block was put in a low temperature environment(−1.0℃)for 48 h,which was then observed using a CT scanner.The thresholds of CT values between air,ice and brine were set to−310 HU and−30 HU for segmentation of the CT image,respectively.The air and brine pores were able to be identified in the CT image,and the two-dimensional morphological characteristics of the pores in ice were analyzed.On the basis of image segmentation,the three-dimensional reconstruction of the ice pores was carried out,and the three-dimensional morphological characteristics of the pores were analyzed.It was found that along the ice thickness,the air area fraction was 5.00%~35.93%,and the brine distribution was discontinuous with maximum area fraction of 0.06%.The cross-sectional shape of the air and brine pores parallel to the ice surface was approximately circular,with a roundness more than 0.60.The equivalent circle diameter of air pore was 1.1~3.2 mm,and that of brine was 0.2~2.0 mm.The equivalent circle diameter of pores was positively correlated with the area fraction and negatively correlated with the roundness.In terms of three-dimensional structure,4 types of air pores were divided according to sphericity(R_(sph))into coronary pores(R_(sph)≤0.25),irregular pores(0.25<R_(sph)≤0.45),strip pores(0.45<R_(sph)≤0.60),and spherical bubbles(0.60<R_(sph)≤1.00).The coronary pore was the largest(average volume(11522.8±5610.2)mm3)with smallest amount,and the spherical bubble was the smallest(average diameter(2.0±1.1)mm)with the largest amount.The brine pores were divided into brine channels(0.45<R_(sph)≤0.60)and brine cells(0.60<R_(sph)≤1.00).The average length of the brine channel was(17.1±12.1)mm,and the average diameter of the brine cell was(1.5±0.9)mm.The amount of brine channels

关 键 词：海冰 孔隙 结构特征 CT扫描 三维重构 

分 类 号：P731.15[天文地球—海洋科学]