Smooth HDPE‐Clay Liner Interface Shear Strengths: Compaction Effects

Abstract

This paper provides two complete sets of shear strength data for smooth HDPE-compacted clay liner interfaces with two significantly different clay liner materials. Data are presented for interface shear strength behavior under as-compacted conditions, and also for conditions representing unconsolidated, undrained shear after sustained presoaking under light surcharges. Samples are tested over a broad range of compaction conditions, and the resulting data show that as compacted HDPE-clay liner interface shear strengths can change by a factor of two or more as a result of relatively minor variations in as-compacted dry density and water content. Moreover, the controlled range of specified field compaction conditions usually employed for waste repository compacted clay liners (in order to optimize ductility and to achieve the low permeabilities mandated by law) appears to encompass the range of compaction conditions over which these significant changes in interface shear strength behavior can occur. In addition, the data peresented show clearly the potentially important impact of wetting of compacted clay liner materials on smooth HDPE-clay liner interface shear strengths.