Sea ice is composed of columnar-shaped grains. To investigate the influence of the loading direction on the uniaxial compressive strength and failure processes of sea ice, field experiments were performed with first-year level ice. Loads were applied both horizontally (parallel to the grain columns) and vertically (across the grain columns) with various nominal strain rates. Two failure modes have been observed: a ductile failure mode at low nominal strain rates, and a brittle failure mode at high nominal strain rates. However, the failure pattern of sea ice was clearly dependent on the loading direction. At low nominal strain rates (ductile failure mode), the sea-ice samples yielded due to the development of wing cracks under horizontal loading and due to splaying out at one end under vertical loading. When sea ice fails in the ductile mode, the deformation is driven by grain boundary sliding under horizontal loading and by grain decohesion and crystal deflection under vertical loading. At high nominal strain rates (brittle failure mode), the sea-ice samples failed in shear faulting under horizontal loading and in cross-column buckling under vertical loading. The nominal strain rate at the brittle–ductile transition zone is about ten times higher under vertical loading.

中文翻译：

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基于现场测量的加载方向对海冰单轴抗压强度的影响

海冰由柱状颗粒组成。为研究加载方向对海冰单轴抗压强度和破坏过程的影响，对第一年冰层进行了现场试验。载荷以不同的标称应变率水平（平行于晶粒柱）和垂直（跨晶粒柱）施加。已观察到两种失效模式：低标称应变率下的延性失效模式和高标称应变率下的脆性失效模式。然而，海冰的破坏模式显然取决于加载方向。在低标称应变率（延性破坏模式）下，海冰样品的屈服是由于在水平载荷下机翼裂纹的发展和由于在垂直载荷下在一端张开而产生的。当海冰在延性模式下失效时，变形是由水平载荷下的晶界滑动和垂直载荷下的晶粒脱聚和晶体偏转驱动的。在高标称应变率（脆性破坏模式）下，海冰样品在水平载荷下发生剪切断层，在垂直载荷下发生跨柱屈曲。在垂直载荷下，脆韧过渡区的标称应变率大约高 10 倍。