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A study on the responseoiclay Iayers subjected.to differential deformations by centrifuAft <br /> model tests was Presented by Jesiberger, eL al._(9), In this study, the effects of overburden anMV <br /> choice of clay liner material on the response of a model liner subjected to deformations were <br /> --- investigated, The test I r1sults sh*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 the m,tterial response, as illustrated in Figure 2. The increased initial lateral <br /> stresses generated wid in the ling as a result of the overburden allowed greater differential <br /> settlement of the clay liner tobefore-tensile stresses could be generated. However, before <br /> reaching such stress levels, 1 dislocation would take place to 'for m- multiple shear <br /> ruptures in the areas of greatest ncr deformation. -Consequently, tensile stresses did not arise <br /> and no tension cracks re ca,catc d <br /> �id once-rupturing.occurred.- It'wa_s observed 1 room the test that <br /> the presence of shear. ptur�cs not affect the performani�c of the:liner as an effective <br /> hydraulic barrier. - <br /> Di er ntial e m - 'r n To evaluate the impact of <br /> differential'settlement the lin a, it is necessary.to.define the configuration of the <br /> deformed liner surface n a A plan. However, the-Elastic Method was developed for <br /> horizontal surfaces. Th model oes not evaluate differential settlements on sloped surfaces. <br /> To evaluate the s ce def rmation of a sloped finer surface, an approximation was made <br /> by projecting the differential setEl meats calculated on a horizontal surface to a sloped surface. <br /> This results in a conservative appxi.mation because the distances between the points along the <br /> sloping surface and the void are t.ways greater than'or equal to those in the horizontal case. <br /> y� Therefore, the differentia settlem nts so calculated in the sloped surface will be slightly y higher <br /> than those in the horizontal case. <br /> Poisson's Ratio sur Lav , et. al. (I5) compared tfTe ma i mum-differential settlement <br /> calculated with the anal "cal el tie model with field measurements for mining subsidence. <br /> With a Poisson's ratio of .5, the ults of the analysis were close to the field results obtained <br /> with a void found at shaf ow d . hs. Tsur Lavie, e-t_ al. thus concluded that the differential <br /> settlement resulting from shallow orris 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 large Poisson's ratio. Following Tsur-Lavie, -et. al's <br /> recommendations, a Poisson's rat1io of 0.5 was used in the design example presented in this <br /> paper. <br /> Calculation Procedures n example of the application of the elastic model to design a liner <br /> system for an actual case where the vertical expansion of an existing landfill is being planned, <br /> is presented below. <br /> EXAMPLE CALCU' LA ON FOR TETE DESIGN OF A SLOPED LINER.SYSTEM <br /> c <br /> DesiPn Problem Avoid 0.9 m (4 feet) long by-0.9 m (3 feet) wide by 1.8 in (6 feet) deep is <br /> 1 <br /> Gcosyntbetics'93-Vancouver.Canada-1503 <br />