混凝土面板堆石坝坝体过水保护

Protection measures for overflowing over concrete faced rockfill dam

天生桥一级水电站混凝土面板堆石坝堆石填筑量大，在大坝填筑施工的第一个汛期，坝体内预留底宽１２０ｍ、边坡１∶１．４的梯形泄槽，该泄槽与导流隧洞联合运行承担１９９６年汛期泄洪任务。泄槽过流按３０年一遇洪水标准加以保护，选用直径大于２０ｃｍ的干砌块石护坡，其表面覆盖铁网，并用钢筋框格固定，泄槽重要部位采用钢筋铁丝笼充填块石加以保护。泄槽过流后，抽水检查结果表明，过流保护面无任何冲刷破坏，达到了安全渡汛的目的。坝体内预留泄槽施工方案，为保证两岸汛期继续填筑施工，满足第二个汛期前的填筑坝体能抵御３００年一遇的洪水起了重要作用。

The amount of rock filling for the concrete face rockfill dam at the Tianshengqiao No.1 Hydropower Station is very huge. Before the first high water period for rock filling of the dam, a trapezoidal discharge channel with its bottom width of 120 m and side slope of 1∶1.4 was provided in the rock fill dam in advance. The discharge channel and the diversion tunnel were used to release the flood during the 1996 high water period. The discharge channel was designed and protected for a 30year frequency flood. The side slopes of the discharge channel were protected by pitched block stone with diameter greater than 20 cm,the pitched block stone was covered by wire mesh and then strengthened by bar mesh, and some important places were protected by barwire cages containing block stones. After flows past through the discharge channel four times during the 1996 high water period, the discharge channel was dewatered and observed. The results indicated that the protected faces of the discharge channel were not scoured. The construction scheme of providing the discharge channel in the rock fill dam played an important role in ensuring the continuous rock filling on both banks during the first high water period and in enabling the rock fill dam raised to retain a 300year frequency flood before the second high water period.