Interaction of surface gravity waves with vertical permeable breakwaters

The protection of the coastline, objects of vital activity, hydrotechnical structures, marine flora and fauna require constant modernization of coastal protection structures, which is due to climate changes and an increase in wave energy of the sea. In recent years, in the development of coastal protection structures, a trend has emerged to use permeable structures, the advantage of which is to improve the ecology of the protected water area, saving construction materials. The article presents the results of experimental researches on the study of the characteristics of the interaction of surface gravity waves with coastal defense structures in the form of permeable vertical breakwaters. The research was conducted in laboratory conditions on models of single-row penetrating breakwaters, which were located in a wave tray. Visual studies were conducted to record the interaction of wave motion with breakwater models, and instrumental studies of the wave field were also conducted. Parameters of wave movement were recorded by specially developed wave height sensors, which were made on the basis of piezoresistive pressure sensitive elements. Photos and video footage allowed us to evaluate the features of the interaction of the wave field with the studied models of permeable breakwaters. Permeable breakwaters of different permeability were used in the experiments. In addition, the vertical permeable breakwaters were closed by impermeable shields at the top of the breakwaters in the area of the water cut. At the same time, impermeable shields were installed at different depths relative to the water level. Hydrodynamic parameters of the wave field in the vicinity of permeable breakwaters (wave heights, periods and lengths, reflection and transformation coefficients, dissipation coefficient of the wave energy) were measured by a group of wave height sensors, which were located in different places in front of the breakwater models, as well as behind them. Integral and spectral characteristics of the wave field were obtained, the dependences of changes in the hydrodynamic parameters of the wave field were determined, depending on the permeability of the breakwater, the relative depth of the water in the wave tray, and the length of the gravitational wave. The degree of protection of the coastline by permeable vertical breakwaters was determined and the maximum values of wave energy dissipation were obtained depending on the shape, size and permeability of the studied models of vertical single-row breakwaters.