Wave dissipation for perforated-breakwater has been investigated in this paper.The relationships of wave transmissivity and reflectivity among the constructed width,the wave steepness and the slope are carefully studied by physical simulation.The results of tests indicate that the perforated-breakwater with 1.2Hm and slope for 1:1.5 has the good characteristics of dissipating waves.

According to the characteristics of flow around the submarine pipeline,using the method which is used to analyze jets,the velocity profiles in the free shear region are obtained through properly simplifying the governing equations.A systematic experimental research on the characteristics of the flow velocity field around the submarine pipelines is conducted by ADV and the rules of velocity and turbulent intensity changes in different flow areas are also investigated.The measure results agree well with the theoretical analysis.These results make a theoretic foundation for the further research on protection technique of submarine pipelines.

By using the cross-section wave model,we make studies of some impacts of single-row artificial reefs on wave reduction and trajectory of water particle motion in this paper.Artificial reefs′ hydrodynamics features such as breaking wave,reducing incoming wave,as well as current pattern and shoreline adjusting behind the artificial reefs are presented.Results of test data analysis show that the artificial reefs weaken wave carrying sediment capacity substantially,so that sediment may deposit in the lee of artificial reefs.To a certain extent,the artificial reefs can prevent the loss of offshore sediment,as the current pattern of back reefs.The research result will provide a scientific basis for beach protection and siltation promotion projects by using artificial reefs.