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一、试验缘由葛洲坝二、三江基岩地层为白垩系下统陆相红色碎屑岩,其中二江地区为五龙组粘土质粉砂岩及其和砂岩的互层;三江主要为砂岩。岩层厚度较薄,质地不均一;倾角平缓(约4—6°);层面胶结不良,且有软弱和泥化夹层存在。坝基岩层上部有10.0米左右的砂砾石覆盖层。曾经在勘探阶段查明,坝基岩层岩性致密,层面闭合,透水性很小或不透水。枢纽主体工程开工后,挖除上部
First, the reasons for the test Gezhouba two, three Jiang bedrock formation of the Cretaceous terrestrial red clastic rock, which the two rivers for the Wulong Formation clayey silt sandstone and interbedded sandstone; Sanjiang is mainly sandstone. The thickness of the rock formation is thin, the texture is not uniform; the dip angle is gentle (about 4-6 °); the layer cementation is poor, and there are weak and muddy intercalations. The top of the dam foundation rock is about 10.0 meters sand and gravel cover. Once found in the exploration stage, the dam foundation rock lithology is tight, the level of closure, water permeability is small or impermeable. After the construction of the main hub project, excavation of the upper part