导流明渠设计问题探讨

The Study of Design of River Diversion Open Channels

采用导流明渠的基本条件是河谷较开阔、河水分叉、枯水期有滩地出露、岸边具有台地、古河道、垭口、河湾等地形;其主要优点是过流能力较大、超泄能力较强、施工条件较好、造价相对较低等。导流明渠一般用于初期导流,中后期导流还需与底孔、隧洞、缺口等其它导流方式组合,以妥善地解决主体工程施工过程中的水流控制问题。导流明渠设计问题是在给定流量下,应使允许流速正好符合水力最佳断面而渠道坡降最经济。通过景洪、观音岩水电站等导流明渠工程实践检验,其成果可供大、中、小型水利工程导流明渠设计借鉴。

The diversion open channel scheme can be adopted for construction of a hydropewer project on condition that river valley is rather wide, river water is braided, flood plain is exposed to some extent during the dry season and there are terraces, old ehannels, saddles and bays on the river banks topographically. It is characterized by large flow capacity, extra- large flood discharging capacity, good construction conditions and relatively low cost. The diversion open channel is usually used for river diversion at the initial construction stage of a hydropower project, and it should be used together with other approaches for river diversion such as a bottom outlet, a tunnel and an opening gap in a combined way at the medium and late construction stages to properly solve the flow control problem in the course of construction of the major works. A diversion open channel should be so designed that its allowable flow velocity just fits its optimum hydraulic cross section and its slope gradient is the most economical. It has been verified by construction practice of the diversion open channels of Jinghong and Guanyinyan hydropower projects. The study results can be used as a reference for de- sign of diversion open channels of large, medium and small hydraulic construction projects.