Filters for Silts and Clays

Abstract

An investigation was made of the filters needed in dams for fine‐grained clays and silts. The “critical” downstream filter in a central core dam should be capable of controlling and sealing a concentrated leak through the core, and should also be stable in conventional laboratory filter tests under a relatively high gradient, such as 1,000. Two different types of laboratory tests were developed to simulate the action of a critical filter (slot and slurry tests). Both gave identical and reproducible results. For fine‐grained clays a sand filter with