Numerical Simulation of Rip-Rap Revetments in Tidal Areas

摘要

Rip-rap revetments are used to protect embankments and coastal shores against erosion. They are built to resist ship and wind induced waves, tidal and ship induced currents, tidally varying water levels and storm surges. In some areas the current basis of rip-rap design is inadequate for dealing with the complexity and variety of boundary conditions, especially in tidal zones. A numerical model has therefore been developed which is capable of simulating the resistance of rip-rap to hydraulic loads. Rip-rap-water-interaction is modelled holistically using two numerical methods. Rip-rap is modelled using the Discrete Element Method (DEM) in three dimensions. The DEM can be used to model rip-rap stones as autonomous objects with all degrees of freedom and realistic movement. The DEM code is coupled with a computational fluid dynamics code (CFD) to account for the influence of the hydraulic loads. Waves and currents acting on the rip-rap stones as well as tidally varying water levels can be generated realistically using time dependent boundary conditions. Additional physical model tests in a laboratory flume, field tests and measurements with instrumented rip-rap stones serve as validation for the numerical model.