Experimental analysis of desiccation crack propagation in clay liners

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 defined as the ratio of the surface crack area A(c), to the total surface area of the clay liner, At. A computer aided image analysis program was used to determine CIF values from scanned photographs of the desiccation process. The variation of the CIF 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 19-hour 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.