Material Selection for the Design of Inclined Covers with Capillary Barrier Effect

摘要

A design procedure is proposed to select landfill cover materials. The specific case ofrninclined covers that limit infiltration due to the capillary barrier effect is investigated. Arnwell known model for the calculation of the diversion capacity is employed. Materialrnselection is mainly based on hydraulic conductivity functions (k-functions). The capillaryrnbreak layer (CBL; bottom layer) of an ideal inclined capillary barrier should include arnmaterial within which capillarity forces are as weak as possible for the infiltration raternconsidered, whereas the moisture retaining layer (MRL; top layer) must be capable torndevelop the strongest capillarity forces possible, for the same infiltration rate. In addition,rnthe MRL must be as permeable as possible, so that water is efficiently drained downslopernand out of the cover. Application of the proposed procedure shows that a combination ofrncoarse materials (such as sand over gravel) diverts water over greater lengths thanrnbarriers employing fine-grained materials as MRL.