柔性防护网孔径对下切河道防护效果的影响OA

When the sediment inflow from the upstream of a river is less than the sediment carrying capacity of the flow,the scouring and erosion effect of the flow on the riverbed will be intensified,resulting in continuous incision.In addition to the traditional common method of river regime control structures,Laying flexible protection network on the riverbed can stabilize the erosion datum,thus effectively enhancing the riverbed impact resistance and inhibiting the riverbed undercutting.In this paper,through 16 groups of indoor flume test,the protection network aperture dn change on the riverbed protection section of the impact of water and sand movement is explored.The results show that:under the same water intensity,as the aperture increases,the protective effect of the flexible network also improves;for flexible network with the same aperture size,as the water intensity θ increases,the protective effect is weakened.Through the test phenomenon,it is found that a scour hole forms downstream of the flexible protection net,and the scouring depth intensifies within a certain distance upstream.Hydraulic calculations reveal that there is a certain head loss between the protection net and the section in front of the net;at the same time,the turbulent vortex caused by the punching pit downstream of the protection net propagates upstream,and the combined effect of these two factors leads to additional scouring effect in front of the net.The results of this research can provide a reference for aperture selection in the application of flexible protection net in actual projects,and provide a research basis for how to inhibit the destabilizing damage of protection net by violent downcutting upstream of the net.