巢湖兆河分洪闸泄流特性试验研究

Model tests on discharge characteristics for Chaohu Zhaohe flood diversion sluice

受周边地形条件及环境限制,巢湖兆河分洪闸与河道呈垂直布置,进流条件不利。针对分洪闸与河道垂直布置这一特征,分别对开敞式和涵洞式分洪闸进行了水工模型进口流态试验分析,结果表明涵洞式分洪闸进流流态优于开敞式分洪闸,能更好地保证各闸孔的均匀进流。针对涵洞式分洪闸方案,研究了分洪闸敞泄和控泄的泄流能力,指出敞泄状态下进口行近流速对流量计算影响明显,在水闸规划设计中,应计入行近流速影响。为改善消能效果及出口水流与下游的衔接,进行了多方案消能防冲改进试验,结果表明尾坎作为一种冲击式消能工布置在挖深式消力池末端,可使出口水流流速分布更加均匀并与下游水流衔接更为平顺,明显增强消能防冲效果。

Restricted by the surrounding terrain conditions and environment, the flood diversion sluice of Chaohu Zhaohe has an arrangement vertical to the axis of the river channel, and thus the river inflow conditions are not favorable. In view of the characteristics of the flood diversion sluice located vertically to the axis of the river channel, experimental analysis of the inlet flow patterns of the flood diversion sluice under the working conditions of open type and culvert type are carried out in a hydraulic model. The model test results show that the inlet flow patterns of the flood diversion sluice under the working conditions of the culvert type are much better than those of the open type release, which well keeps uniform flow incoming into the gate openings. Therefore, aiming at the scheme of the culvert-type flood release, analysis of the discharge capacity of the open release and controlled release of the flood diversion sluice is made, pointing out that the impacts given by the approach velocity upon discharge calculation should be taken into account during the sluice design calculation. In order to improve energy dissipation effects and the outlet flow patterns inflowing into the lower reach, the multiobjective energy dissipation tests with erosion control are made at the same time. The test results indicate that an impact-type energy dissipater having a baffle sill, located on the end of the deep-cut stilling basin, can make the outlet velocity distribution much more uniform and the outlet flow more smooth into the lower flow, and can significantly increase the effects of the energy dissipation and erosion control of the flood diversion sluice.