概述葛洲坝坝址基岩属下白垩纪,地层系砾岩、砂岩、粉砂岩和薄层粘土岩互层。经勘探查明,在第一期工程的基岩中约有60层软弱夹层,按其岩性组合,泥化程度等不同特性,分为五种类型。Ⅰ类—普遍含泥化带的粘土岩夹层有308,227,202,230等4条。Ⅱ类—局部泥化粘土岩夹层有218,212等23条。 Gezhouba dam site overview of the Cretaceous, stratigraphic conglomerate, sandstone, siltstone and thin clay interbedded layers. After exploration, it is found that there are about 60 layers of soft interlayer in the bedrock of the first phase of engineering, which are divided into five types according to different characteristics such as lithology combination and mud degree. Class Ⅰ - common muddy zone with clay rock intercalation 308,227,202,230 and other four. Class Ⅱ - local clay clay rock has 218, 212 and other 23.