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A study on the i esponse oiclay Iayers subjectedto differential deformations by c entrifi <br /> model tests was prise ted by Jesiberger, et. al..(9). In this study, the effects of overburden and <br /> choice of clay liner m itcrial on f the response of a model liner subjected to deformations were <br /> - investigated. The test uits show no tension cracks at the surface. Jessberger, et al, suggested <br /> that the suppression f tension cracking can be explained, in part, by a simple elastic <br /> interpretation of them tenial response, as illustrated in Figure 2. The increased initial lateral <br /> stresses generated wi in the Iin�r as a result of the overburden allowed greeter differential <br /> settlement of the clay Ii er to before tensile stresses could be generated. However, before <br /> reaching such stress 1 eels, I dislocation would take place to form multiple shear <br /> ruptures in the areas of greatest ner deformation. -Consequently, tensile stresses did not arise <br /> and no tension cracks rt creat d once rupturing.Occurred.- It was observed from the test that <br /> the presence of shear. pturics Jid not affect the performance'-of the_liner as an effective <br /> hydraulic barrier. <br /> iffe_r retial e rn m ' ' To evaluate the impact of <br /> differential sefi-lement on the lin r c. it is necessary grad6, any,to define the configuration of the <br /> deformed liner surface n a A plane. However, the-Elastic Method was developed for <br /> horizontal surfaces. Th model oes not evaluate differential settlements on sloped surfaces. <br /> -To evaluate the sm1ace deformation of a sloped liner surface, an approximation was made <br /> by projecting the differential settIl.,ments calculated on a horizontal surface to a sloped surface. <br /> This results in a cone five app ximation because the distances between the points along th* <br /> sloping surface and theyoid are 91ways greater than or equal to those in the horizontal case. <br /> Therefore, the differentia I rets so calculated in the sloped surface will.be slightly higher <br /> than those in the horizon ] case. <br /> Poisson's Ratio sur-Lav e, et. al. (15) compared the maximum differential settlement <br /> calculated with the ana'1� , 'cal el tic model with field measurements for mining subsidence. <br /> With a Poisson's ratio of 0.5, the ults of the analysis were close to the field results obtained <br /> with a void found at shallow depths. Tsu-r-l-avie, el. al. thus concluded that the differential <br /> settlement resulting fromhallow olds was associated with a state of failure extending into the <br /> medium surface. This resulted ii an increase in volume (dilatancy) and, therefore, was best <br /> represented by a model with aI large Poisson's ratio. Following Tsur-Lavie, -et. al's <br /> recommendations, a Poisson's r+ of 0.5 was used in the design example presented in this <br /> paper- <br /> -Calculation Procedures An example of the application of the elastic model to design a liner <br /> system for an actual case where t4c vertical expansion of an existing landfill is being planned, <br /> is presented below. <br /> EXAMPLE CALCULA ON FOR THE DESIGN OF A SLOPED LINER .SYSTEM <br /> Design Problem A void 0.9 m (I feet) long by 0.9 m (3 feet) wide by 1.8 m (6 feet) deep is <br /> Gcosyntbetics'93-Varcouver.Canada-1503 <br />