Hongyuan Liu: Modelling glacier-bed interaction-induced basal deformation, sliding, fracturing and erosion with a hybrid finite-discrete element method
Climate warming accelerates glacier discharge from ice sheets to the oceans, contributing to sea-level rise and posing increasing risks to coastal infrastructure and communities. The glacier discharge is strongly regulated by glacier-bed interactions, which govern the relationship between basal shear stress and sliding velocity, i.e. the so-called slip law. However, the slip law remains a major source of uncertainty in ice sheet models since glacier-bed interactions and the resulting basal deformation, sliding, fracture and erosion are poorly understood. To address this knowledge gap, this study further develops a hybrid finite-discrete element method (HFDEM) to investigate glacier-bed interactions with a focus on modelling interaction-induced basal deformation, sliding, fracturing and erosion processes. HFDEM was originally developed and parallelized using general-purpose graphic processing units (GPGPU) and the compute unified device architecture (CUDA) C/C++ framework. It combines the strengths of the finite element method for continuum deformation with those of the discrete element method for discontinuous behavior, enabling simulation of the progressive failure of geomaterials, which includes intact material deformation, damage evolution, crack initiation, propagation and coalescence, fragment separation, gouge formation and comminution, as well as fragment transport and deposition. This paper first reviews the development and current state of the art of FDEM before introducing several unique or pioneering features of HFDEM, including (semi-)adaptive contact activation approaches, multi-scale heterogeneities, rate-dependent elasto-plasticity models, intrinsic/extrinsic cohesive zone models and efficient fragment-search algorithm. The HFDEM framework is calibrated through simulations of quarrying-induced subglacial erosion in stepped bedrock topography. Finally, the model is applied in three-dimensional simulations to investigate glacier-bed interactions across a range of bed roughness conditions. The modelling results are expected to provide new insights into interaction-induced basal deformation, sliding, fracturing and erosion, ultimately contributing to the development of improved slip laws for next-generation ice-sheet models.