Study on the sediment initiation considering the seepage in the swash zone
CAO Zhigang;WANG Yilun;GUO Zhen;CAI Yuanqiang;LIU Haijiang;Rearch Center of Coastal and Urban Geotechnical Engineering,Zhejiang University;Key Laboratory of Soft Soils and Geoenvironmental Engineering,Minstry of Education;
In order to reveal the effects of seepage on the sediment initiation in swash zone,the experimental and numerical studies were performed in this paper. Firstly,the experiments of solitary wave run-up over permeable and impermeable slope was carried out in an indoor flume,the wave height and flow velocity were measured. Secondly,corresponding numerical simulations were performed and validated by the flume test results. Finally,the influence of seepage on the hydrodynamics in the swash zone and sediment initiation were assessed. The test results show that the asymmetry of wave becomes obvious under the effect of seepage. Strong infiltration during uprush increases the shear stress on the seabed surface,and wave downrush leads to the reduction of seabed shear stress due to the flow loss. It is also found that the seepage changes the effective weight as well as the shear stress of seabed soil particles,which leads to the variations of Shields parameter and greatly increase instability of sediment particles. The change of shear stress over permeable slope is the main reason for the Shields parameter variation of seabed particles. This study can provide guidance for the assessment and treatment of sediment transport in the swash zone.