Microscopic analysis of the influence of soil properties on the suction bucket installation in sand based on the CFD-DEM model

This paper presents a numerical simulation for exploring the characteristics of soils and porewater pressure development during the suction bucket installation in the sand. The dynamic-mesh technology and new drag force model considering irregular particle shapes are adopted in the CFD-DEM model. By comparing the results of experimental and theoretical models, the validation of the numerical program has been proved. Then, this study is motivated by the fact that marine sediments generally exhibit a porosity decreasing with depth because of consolidation under gravity. Results demonstrate that the seabed face porosity is the critical factor that causes differences in penetration resistance and porewater pressure distribution at late installation stages. Additionally, penetration mechanisms with different depths are analyzed by particle migration, porewater pressure distribu-tion, and flow field. Based on microscopic analysis, apart from seepage would induce a noticeable migration of fine particles, the apparent soil-squeezing effect is another essential factor to cause soil displacement and expansion in dense sand. Finally, the bucket can be safely installed in sand, despite the permeability coefficient inside the bucket reaching the critical state. Such a macro and micro insight will further facilitate the design of suction bucket installation, particularly considering the influence of sand permeability.