Laboratory Testing to Optimize Filter Design for Dispersive Clay

December 10, 2020

Dispersive clays can pose a problem for dam designers due to their erodibility and piping potential. Design guidelines commonly used for the designing granular filters provide guidance on specifying a material that will protect a dispersive clay from piping; however filters meeting the recommended gradation may be difficult and/or expensive to produce or procure depending on project conditions. This technical paper presents the results from a laboratory testing program designed to optimize the filter design for a dispersive clay so that locally sourced materials could be used without expensive processing. The program comprised two filter compatibility tests (“continuing erosion filter” and slurry tests) to observe the performance of various filters. The filter tests and performance criteria were based on the work by Foster, Fell, Sherard, Dunnigan and Talbot. The results of the laboratory program are plotted against similar tests results from Foster and Fell and compared to common design guidelines. Friedel, R. and J. Casey. 2016. “Laboratory Testing to Optimize Filter Design for Dispersive Clay,” in: GeoVancouver 2016: 69th Canadian Geotechnical Conference, Vancouver, BC, October 2-5, 2016. Canadian Geotechnical Society.