Study On The Influence Of Wave Transformation And Overtopping Characteristics Of Breakwater On Coral Coast

With the improvement of our Marine resources development ability continuously,Marine economy high speed development,our country in the south China sea reefs is accelerating,the south China sea reef is a typical steep terrain,and the terrain is different with nearshore gentle slope of the continental shelf,the steep terrain makes offshore incident waves occur leading to the wave height increases,the shallow distortion and breakwater is one of the important reef engineering protection facilities,the existence of the breakwater affected the original transmission characteristics of the waves on the reef flat with more overtopping.The wave force and the ovortopping will directly affect the structural safety of the breakwater itself and play a decisive role in the effective operation of other ancillary facilities on the islands and reefs.Therefore,the study on the impact of breakwater on coral reef near the shore on the hydrodynamic characteristics of coral reef has important engineering application value for the construction and maintenance of coral reef engineering.This essay first through physical model experiment on the reef flat with a coral reef near wave motion under the breakwater and to study the change rule of foreshore near the shoreline,reef near coast after foreshore increasing wave buildings near the sea,the low frequency wave plays a leading role in run up,so focus on research under low frequency wave buildings located in different location of the reef flat long wave change rule;Then based on Navier-Stokes equations of three dimensional numerical wave model is set up and use physical experiment data to validate the reliability of the model,by using the numerical model to further study the incident wave height,before the incident wave cycle,reef flat water depth,reef slope slope,breakwater with reef edge distance and wave changes in the new width,focus on research and analysis the changing rule of the average amount of the wave and the wave force,research results could be used to reef engineering for flood control and disaster mitigation and give some reference to wave the structure safety.The results show that the strong wave reflection is caused by the breakwater on the reef flat,and the collision and superposition of the reflected wave and incident wave on the reef flat make the wave surface more disordered.The overtoppingr phenomenon is more obvious when the breakwater is closer to the reef edge reef flat.In the process of wave propagation along the reef,the short wave height decreases continuously along the reef.The low frequency wave height gradually increases along the reef until it reaches its maximum near the coastline.In the process of the breakwater approaching the coastline,the short wave height near the coastline shows a decreasing trend,while the low-frequency wave height has no significant variation rule,and the average water level on the reef flat shows a slight increase trend.By analyzing the wave spectra near the coastline,and using the coherence function and the transfer function,the resonance mode of the low-frequency-wave motion on the coral reef topography was verified,among which,the reef flat resonance existed when the breakwater was closer to the coastline,and the flume resonance existed when the breakwater was closer to the coastline.The overtopping increased with the increase of incident wave height,reef flat water depth,wave period and slope in front of reef.When the relative freeboard height was 1,the overtopping increased by leaps.The overtopping decreases with the increase of the distance between the breakwater and the reef edge and the breackwater width.The influence of the breackwater width of overtopping less obvious.The wave force increases with the increase of incident wave height and the reef flat water depth,but decreases with the increase of the distance between the breakwater distant the reef edge.Because the wave at the reef edge is relatively active,when the breakwater is located at the reef edge,the wave force is relatively large.Finally,based on the research results,a functional relation between the normalized overtopping and the maximum wave force are proposed.