Force And Stability Study Of Dike Under Nonlinear Wave In Shallow Sea

Neritic dike projects protect the coastal areas from attacks of wave and tide,however the safety and stability of dike projects has been seriously threatened by thefrequent occurrences of natural disastersin recent years, such as storm surge disastersand sea level rising by the global warming.The damage of dike projects occurfrequently which caused great national economy loss in the coastal areas.Therefore thesafety and stability of dike projects should be worth further research. With the rapiddevelopment of computational fluid dynamics, the application of numerical wave tankfor wave-structure interaction study has becomeone of the frontier topics recently. Thisthesis uses method of numerical simulation to make a further study on force andstability of dike projects, which provides a certain reference value for safetyconstruction and protection of dike projects.Firstly a numericalwave tank (NWT) which can both generate and absorb waveshas been built with fluid analysis software--Flow-3D. The NWT is based on viscosityfluid theorycombining with the RNGκ-ε model.And finite difference method is usedto solve the Navier-Stokes equations.VOF method is adopted to track thefree surface.Meanwhile secondary development for Flow-3D software to build an active absorptionwave boundaryis proceededin the NWT. Pore structure in the end of the NWThas beenused to dissipate and absorb waves.And cnoidal wave is used to simulate the shallowwater wave.Then validity of the NWT has been proved with groups of wave tests.Secondly, a kind of neritic dike numerical model is built on the basis of the NWT.The reliability of this neritic dike numerical model has been verified by numericalsimulation and test contrast of two kinds of dike section under different waveconditions. The distribution and transformation rule of maximum wave pressure alsohas been analyzed.Thirdly, different kinds of composite dike section including different elevationand width of berm and different slope have been numerical simulated. Then theinfluence of berm elevation, berm width and slope on the maximum wave pressure hasbeen analyzed, and some useful conclusions are obtained.Finally, the destabilization schema of armor blocksof mound type structure hasbeenestablished from the mechanical nature. Then the wave action on armor blocks has been analyzed. The maximum wave negative pressure is analyzedconsideringinfluence of slope of structure, relative depth and wave steepness. And statisticalmethod is used to deduce an empirical expression of envelope curve of maximumwave negative pressure, accordingly anempirical formula of block stability weight isobtained.Meanwhile the extent of most disadvantageous loading on armor blocks hasbeen given which has certain guiding significance for dike engineering applications.