CONSIDERATION ON FACTOR OF SAFETY IN THICKNESS DESIGN OF GEOMEMBRANE USED AS A LINER SUBJECTED TO DEFORMATION

Design methods of thickness, such as Koerner's method, Co-energy method and elastic method proposed by authors, with which geomembrane deforms without any failure in case of differential settlement of subgrade soils are reviewed and meanings of factors of safety, Fs, emploied in design are discussed from a view point of elastic theory. As a result, it is found that Fs or elongation of geomembrane embedded in ground is related to square of Fs for strength, that Fs for thickness coincidence with those for Co energy and for elongation and that stiffer geomembrane, larger overburden pressure or higherfrictional coefficient need thicker thickness.