孔隙对粒状海冰单轴压缩强度影响的数值模拟研究

Numerical study on the effect of pore on the uniaxial compressive strength of granular sea ice

强度是影响海冰与结构物相互作用关系的关键性质之一。海冰内部的卤水胞和气泡等孔隙结构对海冰的强度有重要影响。为从细观角度探究冰内孔隙含量、形状和尺寸等海冰结构参数对海冰力学性质的影响,基于离散元方法,建立了包含孔隙的数值海冰模型,模拟粒状冰在平行和垂直冰面方向加载脆性破坏的单轴压缩过程。孔隙尺寸设置为符合均匀分布、标准正态分布和Gamma分布等不同随机分布类型。数值模拟试验结果表明孔隙率是影响海冰强度的主要因素,海冰单轴压缩强度和弹性模量均随孔隙的增加而减小。当压缩应力达到极值时,冰内裂缝迅速扩展。对于圆形孔隙,裂缝主要沿荷载施加方向开展,因此平行冰面方向试样破坏时多表现为大裂缝;对于椭圆形孔隙,裂缝易扩展形成裂缝带。当孔隙率相同时,孔隙尺寸随机分布类型和位置对单轴压缩强度和弹性模量影响不大,但影响冰内裂缝的扩展方式。

Strength is one of the key properties effect the interaction between sea ice and structures.Brine pockets and air bubbles in sea ice have important effects on the strength of sea ice.In order to explore the effects of ice pore structure such as porosity,shape and size distribution on the mechanical properties of sea ice from a microscopic perspective,a numerical sea ice model including pores was established based on the discrete element method to sim-ulate the uniaxial compression process under brittle failure of granular ice in the directions of horizontal and vertic-al to ice surface.In the numerical simulation,the pore size was set to conform to uniform distribution,standard nor-mal distribution,and Gamma distribution.Results show that porosity is the main factor affecting the strength of sea ice,and sea ice uniaxial compressive strength and elastic modulus decrease with the increase of porosity.When the compressive stress reaches extreme value,the cracks in sea ice develop rapidly.The cracks around circular pores develop mainly along the loading direction,and thus,the final failure of horizontally loaded ice samples exhibits large cracks.While the cracks around elliptic pores are easy to develop into crack band.When sea ice porosity is the same,the types of pore size distributions and locations of pores in ice have little effect on the uniaxial compressive strength and elastic modulus,but the development modes of cracks in sea ice are affected.