二期围堰防渗墙漏失层处理

三峡二期上下游围堰体水下抛填的深度达６０ｍ，其动水中平抛的砂卵石层厚，含砂量低，原河床覆盖层成分复杂，基岩风化层厚度大、块球体较多，防渗墙造孔过程中易产生漏浆。在防渗墙施工前和造孔过程中对漏失层采用预灌浓浆和投置堵料材料快速堵漏的措施，为防渗墙的正常施工创造了条件。

Treatment of Seepage Layers during Construction of Cut-Off Walls

The seepage occurred easily when the walling of the cut -off walls in the up anddownstream phase - II cofferdams at the Three Gorges Project, due to the sand and gravel layer withlower sand content placed from boats in the deep flowing water of up to 60 m, complicated composition of the original overburden, thick weathering rock bed with sound granite boulders in a silt matrix.Before construction of the cut -off walls and during cutting, the quick blocking measures weretaken to the seepage layers, with pre - grouted thick grout mix and other blocking materials, whichcreated a favorable condition for the successful construction of the cut - off walls.