三峡工程二期横向围堰防渗墙设计及施工技术

三峡工程二期上下游横向围堰与混凝土纵向围堰共同形成基坑，保证二期工程施工。上游围堰按挡１００年一遇洪水设计，最大堰高８２．５ｍ。围堰断面要用两侧石碴，中间风化砂堰体，防渗为混凝土防渗心墙上接土工合成材料。防渗墙最大高度７４ｍ。重点论述围堰防渗墙结构设计及施工几个主要技术问题。

Design and construction technique of seepage proof walls in TGP second stage transverse cofferdams

The second stage foundation pit of the TGP will be bounded by the upstream and downstream transverse cofferdams and the longitudinal concrete cofferdam.The upstream cofferdam is designed to retain floods of 100 years recurrence period, with its maximum height of 82.5 m. The transverse cofferdam is placed with stone ballast in its side portions, and with weathered sand in the middle portion. A concrete core wall is provided in the transverse cofferdams for seepage control, with a geotextile diaphragm connected to the top of the core wall. The maximum height of the impervious core wall is 74 m. Several key technical problems on the structural design and construction of the impervious core wall in the transverse cofferdams are expounded in this paper.