Hydraulic Performance of Geosynthetic Clay Liners with Mining Solutions

Abstract

Geosynthetic clay liners (GCL) have been widely used as impermeable materials in landfill and other projects due primarily to their low hydraulic conductivity (k). Recently, GCLs are increasingly considered to contain mining leachates which may result in the degradation of their hydraulic performance. This study reports the hydraulic performance of a GCL under the mining solution from a mine in Hunan Province. Flexible-wall hydraulic conductivity test and free swell index test were conducted on GCL and bentonite specimens. The results indicate that the swell index decreased from 31 mL/2 g (in water) to 22 mL/2 g (under the mining solution). The hydraulic conductivity unexpectedly increased from 3 × 10−11 m/s to 4 × 10−9 m/s when changing the permeable solution from water to the mining solution. While if the GCL specimens were prehydrated with water for two days before contacting mining solution, the k value was decreased to an acceptable level (8 × 10−11 m/s). The greater effective stress also imparts a low hydraulic conductivity, the k value dropped from 4 × 10−9 m/s to 1 × 10−10 m/s when the effective stress elevated from 35 kPa to 200 kPa. The results of this study could provide a helpful reference for the application of GCLs under mining solutions.