Study on the energy dissipation and beach protection mechanism of a new straight double “H” permeable frame

In view of the insufficient overall interlocking ability of traditional energy dissipation and beach protection structures, this paper conducts experimental research on the casting geometric characteristics, hydraulic energy dissipation properties, and anti-erosion and silt-promoting effects of a straight double “H” permeable frame. The research shows that, per unit area, the casting height and porosity of the straight double “H” permeable frame have a certain relationship with the number of casting layers. The casting height and porosity of each layer decrease as the number of casting layers increases and gradually stabilize. The straight double “H” permeable frame plays a role in water resistance and energy dissipation. After casting, the vertical distribution of the time-averaged longitudinal velocity and turbulence intensity in the casting zone undergoes adjustments, and a vertical distribution formula for the time-averaged longitudinal velocity at the center of the casting zone is established. The greater the number of layers, the more significant the reduction in velocity at the bottom of the frame, the greater the increase in velocity at the top, the greater the decrease in turbulent velocity within the frame, and the more pronounced the increase in turbulence intensity near the frame’s surface. When the casting length of the permeable frame reaches a certain distance, its energy dissipation effect tends to stabilize. The frame effectively protects the bed surface, and sediment deposition in the casting zone is significant. Moreover, the protective effect of a two-layer straight double “H” permeable frame is superior to that of a single-layer one. The research results contribute to advancing the study and development of energy dissipation and beach protection structures in hydraulic and waterway engineering.