关键词: 钙质砂, 形状系数, 拖曳力系数, 颗粒沉降, CFD-DEM流固耦合方法

Abstract: Calcareous sand is widely spread in South China Sea. As the sea-filling materials in construction of artificial islands, its permeability has significant influence on the consolidation and settlement of soil mass. The drag coefficient, as the effect of fluid drag force acting on the particle surface, plays an important role on the permeability of calcareous sand, which is not extensively studied by researchers so far. Based on the experimental results of calcareous sand particle settling in various fluids, a new drag coefficient model has been proposed. The new model is now incorporated into the CFD(computational fluid dynamics)-DEM(discrete element method) program and is used to simulate the settling process of calcareous sand particles in fluids. By compared with the experimental results, the CFD-DEM program with new drag coefficient model is validated and it also shows its accuracy in predicting the settling behavior of calcareous sand particles of irregular shape over the existing drag coefficient model without considering the effect of particle shape. On the other hand, the utility of spheres used in CFD-DEM model instead of non-spheres can greatly reduce the computational cost and meanwhile represent the effect of particle shape on the drag force. This CFD-DEM approach is promising and will be applied to the analysis of consolidation, settlement and souring of sea-filling projects with calcareous soils.

Key words: calcareous sand, shape factor, drag force coefficient, particle settling, CFD-DEM coupling approach