大型输水渡槽水流超常波动成因分析与对策

南水北调中线总干渠十二里河渡槽在大流量输水时出现波幅达1.0 m的超常大波动现象,总干渠输水能力受到影响,对相关建筑物构成危害。通过水力学模型试验,复演了原型渡槽大流量输水时的超常大波动现象;分析揭示了渡槽产生超常大波动的成因是渡槽出口的“卡门涡街”及由此引发的渡槽进口左右两槽进流量的周期性变化。从消除渡槽出口墩尾“卡门涡街”波源、阻止渡槽进口前左右两槽进流量发生周期性变化等方面,分别提出了消减渡槽超常大波动的工程措施及闸门调度运行方案。研究结果表明:渡槽内的最大波幅均降至0.2 m以下。闸门调度运行方案在工程现场运用后,渡槽及渠道内的大波浪均得到了有效控制。

Abnormal Water Waves in Large-scale Conveyance Aqueduct:Causes and Countermeasures

Abnormal large water waves with amplitudes up to 1.0 meter were observed under large discharge conditions in the Shierlihe aqueduct, part of the main canal of the South-to-North Water Diversion Middle Route Project. Due to the large water waves, the water conveyance capability of the main canal is affected, and associated structures are endangered. Hydraulic model tests were carried out to reproduce the abnormal water waves observed in the prototype aqueduct. Result reveals that the alternative change of inflow between the left and right ducts induced by Karman vortex street at the exit of the aqueduct is the major cause of abnormal water waves with large amplitudes in the aqueduct. By eliminating the wave source, i.e., Karman vortex street at the exit pier of the aqueduct and preventing the alternative change of inflow conditions in the left and right ducts at the aqueduct entrance, engineering measures and scheduled gate operation scheme are proposed to reduce the abnormal water waves in the aqueduct. It is found that the maximum wave amplitudes in the aqueduct can be reduced to below 0.2 meter under all discharge conditions. The proposed gate operation strategy has been applied to the prototype project, and the abnormal water waves in the aqueduct and canal are well controlled.