Study On Hydraulic Characteristics And Stability Of The Circular Interlocking Ecological Revetment Structure

As the longest river in China,the Yangtze runs through 11 provinces and cities,providing rich nourishment for Chinese civilization.With the development of society,the Yangtze River,as an inland "golden waterway",goes straight to the East China Sea and is navigable in all seasons below Yibin,giving great impetus to the development of the Yangtze River Economic Zone.Since the completion of the Three Gorges Reservoir,water and sand conditions in the middle and lower reaches of the Yangtze River have changed and bank erosion has become serious,and various shore protection projects have been constructed along the course to maintain the stability of the Yangtze River and the safety of the waterway.However,traditional bank protection projects tend to focus more on remediation effects,thus neglecting ecological development along the Yangtze River.Therefore,it is important to propose a bank protection structure that can both stabilize the banks and create ecological value for the sustainable development of the ecological environment along the Yangtze River.This thesis reviewed the types and development of ecological revetments in the country and abroad,a circular interlocking ecological revetment structure was proposed.The slope without the circular interlocking ecological revetment structure was compared with the slope of the circular interlocking ecological revetment structure,and the changes in the hydraulic characteristics of the revetment structure were analysed by fixed-bed tests,the stability and scouring characteristics of the circular interlocking ecological revetment structure were analysed by dynamic-bed tests.The main findings are as follows:(1)The water surface line distribution pattern of the circular interlocking ecological revetment structure is similar to that of the bank slope without revetment blocks,with the water level of the nearshore flow slightly greater than that of the main channel.In the middle and upper reaches of the bank slope,water levels rises in near-shore areas.The transverse and longitudinal drops in the water surface also increase correspondingly.(2)Compared to slopes without riparian blocks,the circular interlocking ecological riparian structure reduces the velocity of the near-shore flow.In the riparian zone,the deceleration rate varies from small to large and tends to a constant value along the flow direction.For the same water depth,the deceleration rate first decreases with increasing flow rate and then tends to a constant value;when the average flow velocity of the section is the same,the deceleration rate gradually decreases with the increase of water depth.(3)The effect of the revetment structure on turbulence intensity and turbulence energy is significant.The turbulent intensity and turbulent energy of the near-shore flow increases in the circular interlocking barrier compared to the slope without the barrier,while it decreases near the foot of the ramp.The distribution of turbulent intensity and turbulent energy is similar in all three directions,with the turbulence being more intense near the bank slope and gradually decreasing and stabilizing away from the slope towards the center of the river.The turbulent dynamic strength and turbulent kinetic energy around the revetment structure are positively correlated with the flow velocity and negatively with the water depth.(4)There are two main forms of instability in the circular interlocking ecological revetment structure: first,local instability caused by the sinking of the revetment structure due to river erosion,and secondly,instability caused by the overall downward sliding of the structure due to the deformation of the foot of the slope by erosion.The addition of stone throwing at the front and rear of the interlocking ecological revetment structure and at the foot of the slope can greatly improve both of these structural instabilities.(5)The circular interlocking ecological revetment structure has a certain effect of preventing scouring and promoting siltation on the bank slope.After the deposition blocks are laid,the scouring depth and scouring area of the bank slope are significantly reduced,and sediment is mainly accumulated inside the circle.The sedimentation area of the bank slope is negatively correlated with the flow velocity,but is positively correlated with the water depth,while the erosion depth is positively correlated with both the flow velocity and water depth.The location of the maximum scour depth is concentrated at the junction of the bank slope and the water surface.