Hydraulic Conductivity of Compacted Clay Liners Subjected to Alternate Wet-Dry Cycles
摘要
Compacted clay liners and covers placed in landfills are subject to alternate cycles of wetting and drying, causing a change in their hydraulic behaviour. The experimental study presented here was carried out on a compacted red soil-bentonite mixture subjected to alternate wet-dry cycles, using distilled water and 0.4 M CaCl2 solution as inundating fluids. Hydraulic conductivity tests were executed using two methods: rigid wall and flexible wall permeability tests, to understand the effect of permeameters along with the permeating fluid on the hydraulic behaviour. The tests were conducted after each wetting cycle utilizing the same permeating fluid as used for inundation, at a hydraulic gradient of 20. The flexible wall tests were also conducted under three different confining stresses: 20, 50 and 100 kPa. The hydraulic conductivity was seen to increase with the wet-dry cycles and the concentration of the inundating fluid, with both types of testing, and the values predictably reduced, as the applied confining pressure increased from 20 to 100 kPa. However, the impact of confining stresses was seen to increase with the number of alternate wet-dry cycles, especially for specimens inundated with salt solutions.