assessment of cover layers using an instrumented 2d channel with control for climate conditions

Cover layers are paramount in landfill performance as they control infiltration (and leachate generation), fugitive emissions, and waste oxidation. however, wetting/drying cycles and differential settlements due to waste mass loss impose a set of different mechanical demands on these structures, resulting in crack propagation and performance losses. constructing a large instrumented 2d channel with boundary control for rainfall, insolation, temperature, and air relative humidity (rh) and monitoring moisture content, suction, runoff, and bottom drainage can enable reliable cover assessment under different climate conditions. the results of two long-term tests on capillary (cb) and conventional (cv) barriers, focusing on semi-arid climate conditions, were used to evaluate the rh influence on cover layer performance. the cv test, performed on arid conditions, identified eight large cracks crossing the clayey layer in the first fifteen testing days. in contrast, the cb test, performed with higher rh, identified only two main cracks. infiltration water reached the clayey layer bottom on day 127 in the cb test, and the total leaked water corresponded to 5 mm or about 1.89% of the amount of rain. in contrast, 14.4 mm, corresponding to about 10.7%, was monitored for the monolithic barrier. the channel behavior was considered very promising as it enables the evaluation of different cover layouts under controlled climate conditions close to those at the landfill site and can be used to feed numerical hydro-mechanical simulations.