Abstract:When performing seepage tests,hydraulic saturation is used for transitional rockfill,main rockfill and secondary rockfill with high permeability permeable. While for bedding rockfill which has moderate or even low permeability,vacuum saturation can be used to save much time. Due to some reasons such as geological structure,usually there are mudstone interlayers in rock. Therefore,it is necessary to study the influences of saturation manners and mudstone content on seepage coefficient of rockfill. Utilizing osmoscope for coarse-grained soil,a series of permeability tests are performed on the filling material of the pumped storage power station dam in Mashan,Wuxi City. Saturation manner hardly affects the seepage coefficient of rockfill;and the seepage coefficient decreases when the mudstone content in rockfill increases. When the mudstone content is high enough,the seepage coefficient decreases to a very low value. Furthermore,the relationship between seepage coefficient of rockfill and mudstone content is negative exponent.