Piping in Earth Dams Constructed of Dispersive Clay; Literature Review and Design of Laboratory Tests.

摘要

It was assumed when empirical piping criteria were developed 25 yr ago that soil type and method of construction were the main parameters controlling the resistance of homogeneous earth dams to piping failure. Research on piping failure in earth dams constructed of dispersive clay (a particular type of soil in which the clay fraction erodes in the presence of water by a process of deflocculation) was initiated in Australia about 15 yr ago. This research has resulted in a method of analysis to assess the susceptibility of a homogeneous earth dam, constructed of predominately illite or montmorillonite clay, to dispersive clay piping. The first study of dispersive clay in the United States, reported in 1972, developed a relationship between percent sodium and total soluble salts in the soil pore water extract and field performance of earth dams as evidenced by piping failure or rainfall erosion damage. This research has demonstrated the usefulness of the pinhole erosion test as a method of identifying dispersive clays, shown the feasibility of using filters to prevent piping in dispersive clays, and indicated that stabilization of dispersive clays is possible.