| As a transition zone connecting the water-terrestrial ecosystem,river bank revetment undertakes important functions such as protecting bank slopes,stabilizing river regimes,and providing habitats for aquatic organisms.In the past,traditional revetment projects only considered the stability and safety of the project.Most of the rigid revetments were built with rocks,concrete and other materials,which destroyed the stability of the river ecosystem and even threatened the ecological environment on which humans depend.The ecological bank protection project is a comprehensive renovation project that comprehensively utilizes modern water conservancy,ecological landscape science,biological science,and environmental science,combined with local shoreline characteristics and biological resources to achieve effective protection,rich biological species,and connotative landscapes.Therefore,studying the impact of ecological revetment structure on water flow characteristics under the action of different currents is of great significance to the research and development of revetment engineering.Based on the collection of a large amount of ecological revetment research data,this paper selects three kinds of porosity(36% 53.8% 75.1%、 、 square thin-walled perforated ecological revetment structures,through the combination of clear water fixed-bed flume model test and theoretical analysis,the water flow characteristics,shear stress distribution and turbulence characteristics around the bank slope before and after the bank revetment under different water depths and different flow rates are systematically studied.The main conclusions drawn in this article are as follows:(1)The ecological revetment structure can significantly increase the upstream water level,reduce the vertical drop of the water level,and increase the water depth in the mainstream area.The change trend of the water surface line under different porosities is basically the same,and the revetment block with large porosity(P=75.1% retains water slightly better;(2)The ecological revetment structure has a significant impact on the flow velocity,especially at the relative depth of 0.8H in the revetment area,which can effectively reduce the flow velocity in the bank slope area and increase the flow velocity in the mainstream area,the deceleration effect of the revetment block with large porosity(P=75.1%)is more obvious;(3)The ecological bank protection structure can significantly increase the shear stress of the bank slope.The maximum shear stress occurs near the slope and groove interface,where the stress gradient is the largest and the shear failure is most likely to occur.When the water depth is small,the maximum shear stress varies with the slope.The porosity increases with the increase,and the influence of porosity on the shear stress decreases with the increase of water depth;(4)The overall turbulence intensity around the ecological revetment structure increases with the increase of flow and porosity.The maximum turbulence intensity appears at the left part of the interface between the bank slope and the main trough.(5)The porous structure in the ecological bank protection structure can provide a suitable environment for aquatic organisms to inhabit and grow.The analysis focuses on the impact on fish spawning grounds,and the porosity P=53.8% is more conducive to fish reproduction and development.In general,the square thin-walled perforated ecological bank protection structure in this study has a greater impact on the water flow structure near the bank slope,the water body is intensively sheared and mixed at the interface of the slope and trough,and the water flow directly scouring the bank slope is greatly reduced,it fully proves the bottom protection and siltation promotion effect of the revetment structure.On the whole,the anti-erosion and deceleration effect of the revetment structure with large porosity is better. |
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