高心墙堆石坝坝基防渗墙与心墙连接方案研究

Research on Conjoining Scheme for Anti-Seepage Wall of High Rockfill Dam with Earth Core

深厚覆盖层坝基上的高心墙堆石坝越来越多地采用两道防渗墙的设计方案。防渗墙与土质防渗体连接处是抵御渗透破坏的关键部位,该部位的混凝土结构设置方案优化是防渗设计的重点内容。阐述了瀑布沟电站心墙堆石坝混凝土防渗墙与土质心墙几种连接方案的设计比选过程,重点研究了防渗墙和廊道完全被高塑性黏土包裹和仅顶部被高塑性黏土包裹两个优化方案中心墙底部的孔隙水压力和渗透坡降的性状,表明这两个方案都是可行的。连接部位的渗透坡降是非均匀的,混凝土结构顶部的渗透坡降较大,心墙底部出口处的渗透坡降较小;坝体与两岸相接部位心墙底部渗流出口处的渗透坡降最大;高塑性黏土仅设置于混凝土结构顶部有利于心墙变形和施工进度,推荐设计采用。

In the design of high rockfill dams on the deep and thick gravel-sand foundation with earth core, double anti-seepage walls will be more frequently used. The conjoining area of the anti-seepage soil body and the concrete wall is the key part to prevent seepage failure, and the optimization of structural arrangement in this area is the emphasis in a design process. In this paper the process of design scheme of the conjoining area in the Pubugou Rolled Earth-rock Fill Dam is presented, and the research focused on the pore pressure and seepage gradient character of two optimum schemes, i.e. one is that the cutoff wall and the gallery are entirely packed by clay, and the other, those are partially packed on the top by clay. It is indicated that the two schemes are both suitable. Seepage gradient in the conjoined area is inhomogeneous around the concrete structure. Seepage gradient at the top of the structure is much bigger than that at the outlet of the earth core base. Using high plastic clay package only on the top of the concrete structure is favorable to the settlement of the earth core and the construction schedule, so it is recommended to be used in the design.