Investigations on statically stable, sloping, rubble mound coastal structures

The ability to predict the level of reflection, transmission, run-up and run-down for various types of coastal structures plays an important role in the assessment of their hydraulic performance. These parameters together with the hydraulic, geotechnical and structural stability of the individual components and of the structure as a whole determine the overall performance of the structure. The porosity and permeability of the structure too has a significant influence on the hydraulic performance and the economics of construction. This study has done a literature review and presents the results from a study of the hydraulic performance of a wide range of structures used in harbour and coastal engineering. The results of two detailed hydraulic model investigations of trapezoidal layered breakwaters at scale 1:20 (tested at LHI). The results are compared with a model investigation done on a homogeneous breakwater at scale 1:40 (tested at Imperial College, London). The investigations were designed to obtain a full profile of the energy dissipation characteristics of the structures tested, including the damping of waves as they propagate through the structure. The results are discussed in the context of the importance of porosity and permeability of wave absorbing structures, their application in practice and further research. Keywords Breakwaters, Reflection, Transmission, Dissipation, Porosity, Permeability, Scale Effect