A stress-based poro-damage phase field model for hydrofracturing of creeping glaciers and ice shelves
A stress-based poro-damage phase field model for hydrofracturing of creeping glaciers and ice shelves
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DOI：
10.1016/j.engfracmech.2022.108693
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发表时间：
2022-08
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影响因子：
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通讯作者：
Theo Clayton;R. Duddu;Martin Siegert;E. Martínez-Pañeda
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文献类型：
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作者：
Theo Clayton;R. Duddu;Martin Siegert;E. Martínez-Pañeda
有一种计算模型的需求，能够预测冰川中融水辅助的裂缝生长。冰川和冰盖的质量损失是海平面上升的最大原因，而由于水力破裂导致的冰山崩解是最突出但鲜为人知的冰川质量损失过程之一。为了克服经验和分析方法的局限性，我们提出了一个新的基于相场的计算框架来模拟接地冰原和浮冰架的裂缝生长。该模型结合了机械模拟地表和基底裂缝水力破裂所需的三个要素：(i)包含冰的非线性粘性流变的本构描述，（ii）能够捕捉任意复杂性裂缝现象的相场公式，例如3D裂缝相互作用，以及（iii）孔隙-损伤表示，以解释融水压力对裂缝生长的作用。采用基于应力的相场模型来降低长度尺度的敏感性，以应对大规模的冰山崩解，并充分预测不可压缩固体拉应力区域的裂缝生长。通过处理涉及单个和多个裂缝的2D和3D案例研究，并考虑接地和浮动条件，展示了所提出的计算框架的潜力。当具体到与之相关的理想情景时，模型结果显示与分析方法有很好的一致性。更重要的是，我们展示了该模型如何用于提供浮动冰架和3D冰盖中裂缝相互作用的第一个计算预测，为这些现象提供了新的视角。此外，裂缝的蠕变辅助成核和生长在一个现实的几何模拟，对应于赫尔海姆冰川。所提出的计算框架为冰山崩解建模开辟了新的视野，并且由于其包含不可压缩行为的能力，可以很容易地纳入预测海平面上升的数值冰盖模型。
There is a need for computational models capable of predicting meltwater-assisted crevasse growth in glacial ice. Mass loss from glaciers and ice sheets is the largest contributor to sea-level rise and iceberg calving due to hydrofracture is one of the most prominent yet less understood glacial mass loss processes. To overcome the limitations of empirical and analytical approaches, we here propose a new phase field-based computational framework to simulate crevasse growth in both grounded ice sheets and floating ice shelves. The model incorporates the three elements needed to mechanistically simulate hydrofracture of surface and basal crevasses: (i) a constitutive description incorporating the non-linear viscous rheology of ice, (ii) a phase field formulation capable of capturing cracking phenomena of arbitrary complexity, such as 3D crevasse interaction, and (iii) a poro-damage representation to account for the role of meltwater pressure on crevasse growth. A stress-based phase field model is adopted to reduce the length-scale sensitivity, as needed to tackle the large scales of iceberg calving, and to adequately predict crevasse growth in tensile stress regions of incompressible solids. The potential of the computational framework presented is demonstrated by addressing a number of 2D and 3D case studies, involving single and multiple crevasses, and considering both grounded and floating conditions. The model results show a good agreement with analytical approaches when particularised to the idealised scenarios where these are relevant. More importantly, we demonstrate how the model can be used to provide the first computational predictions of crevasse interactions in floating ice shelves and 3D ice sheets, shedding new light into these phenomena. Also, the creep-assisted nucleation and growth of crevasses is simulated in a realistic geometry, corresponding to the Helheim glacier. The computational framework presented opens new horizons in the modelling of iceberg calving and, due to its ability to incorporate incompressible behaviour, can be readily incorporated into numerical ice sheet models for projecting sea-level rise.