瀑布沟水电站量水堰防渗墙深度优化分析

Optimization Analysis of Depth of Cut-off Wall of Measuring Weir at Pubugou Hydropower Station

量水堰的设立可以对瀑布沟水电站大坝的非正常工作状态做出正确预警,随着量水堰防渗墙深度增长会大大增加经济成本;因此,探寻合适的悬挂式防渗墙方案不但可以使量水堰达到预警作用还可以降低投资成本。研究表明:量水堰工作状态取决于堰顶高程与下游水位之差和防渗墙深度两个主要因素。通过现场勘测数据确定了瀑布沟大坝坝基覆盖层和两岸山体的水文地质分区及其渗透系数取值范围,对比不同量水堰防渗墙深度、不同堰顶高程的阻水效果,并综合考虑经济效益,最终确定堰顶高程674 m,防渗墙底部深入原河床地面线以下10 m的施工方案。

The establishment of measuring weir can make an accurate early warning for abnormal working condition of the dam of the Pubugou Hydropower Station,however,the economic costs can increase significantly as the depth of the measuring weir impermeable wall.Therefore,exploring a suitable suspended cut-off wall program can not only make the measuring weir achieve the early warning function but also reduce the investment costs.The study shows that the working condition of the measuring weir depends on two main factors:the difference between the weir top elevation and the downstream water level,and the depth of the cut-off wall.The hydrogeological zoning and the range of the permeability coefficient of the Pubugou Dam foundation overburden and the mountains on both sides of the river were determined in the range through field survey data.The depth of the impermeable wall of the measuring weir,the water blocking effect of the weir top elevation,and the economic benefits were compared comprehensively.Eventually,the construction program was determined to be the weir top elevation of 674m,and the bottom of the seepage control wall was 10m deep below the original riverbed ground line.