淹没植被明渠边界切应力试验研究

Experimental Study on Boundary Shear Stress of Open Channel with Submerged Vegetation

生态河道中的植物在净化水质的同时增大了河道阻力,是抬高河道水位、影响河道行洪安全的原因之一。采用塑料草模拟植被,建立横断面为梯形的明渠水槽,研究植被淹没情况下明渠水深、流速以及植物间距对明渠切应力的影响。通过对研究水体的受力分析,推导出床面平均切应力计算公式;根据试验结果,计算得出不同条件下的边界平均切应力,分析不同水流条件、不同植物密度情况下明渠边界切应力的变化规律。结果表明:水流流速以及植物布置间距对明渠边界切应力影响较大,水深对边界切应力影响相对较小。

The plants in the river not only purify the water quality,but also increase the resistance of the river and raise the water level.Therefore,the resistance of river with plants is one of the current research hot spots.Plastic grass was used to simulate vegetation,and an open channel with trapezoid cross section was built to study the influence of water depth,velocity and plant spacing to the resistance of open channel with submerged vegetation in this paper.Through the force analysis of the research water body,the calculation formula of the average shear stress of the bed surface was derived.According to the test results,the average shear stress of the boundary under different conditions was calculated and the change rule of the shear stress of the open channel under different flow conditions and different plant densities was an⁃alyzed.The results show that the flow velocity and plant spacing have a great influence to the boundary shear stress,while the water depth has a relatively smaller influence to the boundary shear stress.