EXPERIMENTAL ANALYSIS OF DESICCATION CRACK PROPAGATION IN CLAY LINERS¹

Abstract

A laboratory investigation on a scaled model of a landfill liner was conducted to provide data regarding the occurrence and extent of desiccation cracking of prototype liners. The crack intensity factor, CIF, was introduced as a descriptor of the extent of surficial cracking. CIF is defmed as the ratio of the surface crack area A, to the total surface area of the clay liner, At. A computer aided image analysis program was used to determine CII' values from scanned photographs of the desiccation process. The variation of the CII' was related to duration of drying and measured soil moisture suctions.The soil of this investigation experienced significant cracking, with crack widths approaching 10 mm in the first drying cycle and penetration through the entire 16 cm thickness. Crack propagation was limited to a very intense period of the desiccation process.Nearly 90 percent of the crack development occurred during a 19hour time period, although the total duration of the desiccation cycle was approximately 170 hours. The soil moisture suction changed by only 2 bars during the period of rapid crack growth, although it changed by more than 40 bars during the period of reduced growth.

Landfill cap models under simulated climate change precipitation: impacts of cracks and root growth

“…However, in the NP model, the majority of cracks developed only partially penetrated each layer. Cracking of the barrier layers in a landfill cap can decrease the function of the cap and jeopardise the integrity of the whole containment system owing to increased infiltration (Miller et al, 1998). Yesiller et al (2000) reported a similar observation in landfill caps where desiccation cracks penetrated the entire depth of a 180 mm compacted clay cover.…”

“…When crack formations in composite liners were studied by applying heat to soil samples, Bowders et al (1997) reported a 20 mm deep crack formed on the first day, which eventually grew in depth to 150 mm after 8 weeks. In another landfill cap study where desiccation crack propagation from wetting and drying was examined, a severe crack that was about 10 mm wide after the first drying cycle reached a depth of 160 mm within a period of 170 h. Close to 90% of the desiccation cracking occurred within a 19 h period (Miller et al, 1998). Rayhani et al (2008) report that permeability increases for some highly plastic soils during cycles of wetting and drying are not significant, despite the presence of visible cracks after drying cycles.…”

Effects of tire chips on shrinkage and cracking characteristics of cohesive soils

“…Desiccation induces cracks in the soil structure and moisture can migrate into the landfill through the cracks and leads to the generation of more waste leachate. Ultimately the potential of soil and groundwater contamination increases [1]. Several researchers have indicated that the hydraulic conductivity of clay liners having desiccation cracks increased significantly while soil strength decreased [2][3][4].…”

Hydromechanical behavior of a quasi-saturated compacted soils on drying-wetting paths-experimental and numerical approaches

“…In the laboratory, the characterization of compacted soil is generally carried out by standardized Proctor tests [1,2,3]. In the literature, many studies are devoted to the behavior of compacted soils on drying wetting paths [4,5] and the induced cracking desiccation [6,7]. This paper presents an experimental and numerical investigation carried out on a compacted marl on dryingwetting paths.…”