Shear Strength Behavior of Two Landfill Clay Liners

Direct shear tests were conducted to obtain both the shear strength of compacted clay liners (CCLs) specimens and the interface shear strength between compacted clay liner and base soil. These experiments were conducted under the conditions of five different water contents. The experimental results show that shear strength of both CCLs and CCLs/base interface decreases with the increase in the water content of CCLs and base soil. In addition, the considerate concentration of NaCl in leachate has no deteriorating effect on the shear strength of liners. Triaxial shear tests were also conducted on clay liner specimens to obtain total and effective shear strength under a fast compression. The shear strength parameters with total stress are ϕ =18.5° and c =30 kPa for clay bentonite, and ϕ =48.5° and c =90 kPa for sand bentonite and those with effective stress are ϕ'=27.2° and c' =25 kPa for clay bentonite, and ϕ '=35° and c '=100 kPa for sand bentonite, respectively. These results indicate that the compacted clay bentonite shows normal consolidation, but that the compacted sand bentonite exhibits over consolidation.