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11.
北极夏季海冰单轴抗压强度研究 总被引：2，自引：2，他引：0
The results on the uniaxial compressive strength of Arctic summer sea ice are presented based on the samples collected during the fifth Chinese National Arctic Research Expedition in 2012(CHINARE-2012). Experimental studies were carried out at different testing temperatures(-3,-6 and-9°C), and vertical samples were loaded at stress rates ranging from 0.001 to 1 MPa/s. The temperature, density, and salinity of the ice were measured to calculate the total porosity of the ice. In order to study the effects of the total porosity and the density on the uniaxial compressive strength, the measured strengths for a narrow range of stress rates from 0.01 to 0.03 MPa/s were analyzed. The results show that the uniaxial compressive strength decreases linearly with increasing total porosity, and when the density was lower than 0.86 g/cm3, the uniaxial compressive strength increases in a power-law manner with density. The uniaxial compressive behavior of the Arctic summer sea ice is sensitive to the loading rate, and the peak uniaxial compressive strength is reached in the brittle-ductile transition range. The dependence of the strength on the temperature shows that the calculated average strength in the brittle-ductile transition range, which was considered as the peak uniaxial compressive strength, increases steadily in the temperature range from-3 to-9°C. 相似文献
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为提高冻融模型与原型的相似程度,提出冻结指数相似比和实验室修正系数的概念及计算方法。以哈尔滨地区黄土为试验材料,将该地区2010–2012年3年日平均气温进行线性简化,基于含相变热传导的微分方程基础上,采用相似理论,在几何、温度和时间比尺约束下对密度为1.60 g/cm3、含水率为20 %的试样进行冻融循环模型试验,确定实验室修正系数K值为1.13,得到冻结指数相似比CI为1:102.5。对冻融阶段温控历时进行优化,进行冻融循环模型试验。通过对比可知,优化后模型的最大冻深值为21.33 cm,与模型预定值20 cm相差仅6.5 %;优化后冻融模型弥补了太阳辐射对冻深的影响,一个冻融周期由108.14 h减少为84.53 h。以实验室修正系数K和冻结指数相似比CI优化冻融过程的各温控阶段历时合理,显著提高了冻融模型的最大冻深和冻融过程在几何比尺和时间比尺上的相似度。 相似文献
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引入拖曳系数参数化的海冰自由漂流模拟研究 总被引：2，自引：0，他引：2
Many interesting characteristics of sea ice drift depend on the atmospheric drag coefficient(C_a) and oceanic drag coefficient(C_w).Parameterizations of drag coefficients rather than constant values provide us a way to look insight into the dependence of these characteristics on sea ice conditions.In the present study,the parameterized ice drag coefficients are included into a free-drift sea ice dynamic model,and the wind factor α and the deflection angle θ between sea ice drift and wind velocity as well as the ratio of C_a to C_w are studied to investigate their dependence on the impact factors such as local drag coefficients,floe and ridge geometry.The results reveal that in an idealized steady ocean,C_a/C_w increases obviously with the increasing ice concentration for small ice floes in the marginal ice zone,while it remains at a steady level(0.2-0.25) for large floes in the central ice zone.The wind factor α increases rapidly at first and approaches a steady level of 0.018 when A is greater than 20%.And the deflection angle θ drops rapidly from an initial value of approximate 80° and decreases slowly as A is greater than20%without a steady level like α.The values of these parameters agree well with the previously reported observations in Arctic.The ridging intensity is an important parameter to determine the dominant contribution of the ratio of skin friction drag coefficient(C_s' /C_s) and the ratio of ridge form drag coefficient(C_r'/C_r) to the value of C_a/C_w,α,and θ,because of the dominance of ridge form drag for large ridging intensity and skin friction for small ridging intensity among the total drag forces.Parameterization of sea ice drag coefficients has the potential to be embedded into ice dynamic models to better account for the variability of sea ice in the transient Arctic Ocean. 相似文献