Impact Load by an Ice Floe against a Structure

我们利用自由下落的浮冰在不同的条件下进行了关于浮冰对建筑物的冲击的中等规模的实验。冲击载荷随冰温的降低而线性增加，推测冰温对冲击载荷的影响大于对抗压强度的影响。在本研究的试验条件下，冲击载荷受冰温的影响大于动能的影响。当冰引起脆性破坏/裂解，碎片在与结构物碰撞后自由移动时(特别是当浮冰相对于结构物较大时)，冲击载荷或冲量比没有破坏的情况小，并成为一个常量，与动能或动量大小无关。我们还对木材和钢材以及海冰进行了实验，考虑了与海啸有关的碎片，如木材、集装箱和船只。对于没有脆性破坏的木材和钢，它们的冲击载荷通常比海冰的冲击载荷大一个数量级。我们还开发了一种用DEM模拟结构冲击和破坏的数值方法，得到了估算海冰冲击载荷的实用工具。

We performed medium-scale experiments regarding the impact applied by ice floes against a structure using free-falling ice floes under various conditions. The impact load increased linearly with decreasing ice temperature ; accordingly, it was presumed that the effect of ice temperature on the impact load was larger than that on compressive strength. The impact load was also more strongly influenced by ice temperature than by kinetic energy under the test conditions of this study. When ice causeed brittle failure/splitting, and fragments moved freely after impact with a structure (especially when the ice floe is large compared to the structure), the impact load or the impulse was small compared to cases without failure, and became a constant value regardless of the level of the kinetic energy or the momentum. We also made experiments regarding timbers and steels along with sea ice, considering tsunami-related debris such as timber, containers and vessels. In case of the timbers and the steels without brittle failure, their impact loads were generally one order of magnitude larger than those of sea ice. We also developed a numerical method using DEM to simulate the impact on a structure and its failure, and we obtained a practical tool for estimating an impact load of sea ice.