For a cost reduction of block-mound construction, an accurate prediction of sedimentation of blocks is essential. In this study, high-resolution calculations by using computational grids as fine as a few tenth of block length are performed. A hybrid turbulence model, such as the Detached Eddy Simulation (DES) is introduced to describe details of turbulent flow fields around blocks. The developed numerical code is verified by comparing its results with the experiment of sedimentation of a single block. Then, numerical simulation of sedimentation of multiple blocks is performed to show some parts of characteristics of turbulent flow structure.