SEISMIC DISTRESS AND PROTECTION OF FLEXIBLE MEMBRANE LINERS OF SOLID WASTE LANDFILLS

Seismic distress of solid waste landfills may result from any of the two consequences of a seismic event: (a) the transient ground deformation related to seismic wave propagation, (b) the permanent ground deformation caused by abrupt fault dislocation. Design provisions for solid waste landfills prohibit the construction of landfills in the vicinity of an active fault aiming to prevent the latter. Nonetheless, the impact of applied permanent deformation on the system components of landfills and on the waste mass has not been fully demonstrated yet. For this purpose, efficient finite-element analyses were performed, taking also into account the potential slip displacement development along the interfaces formulated on each side of the flexible membrane liner (FML). It is shown that base fault dislocation causes significant plastic strains at each one of the components of the waste landfill. Therefore, four hazard levels were identified considering the most critical aspects for the safe function of a landfill. Subsequently, the ability of several potential mitigation measures to reduce the permanent deformation was examined, by developing and analyzing elaborate finite element models. These measures were developed in accordance to the two basic components of typical composite liners, i.e., clay and geomembrane. Evidence is provided that the efficiency of the proposed measures on minimizing the impact of the applied fault displacements is significant, since the deformations of the FML were remarkably reduced. Hence, the results of this study justify the applicability and effectiveness of mitigation measures for the protection of FML against fault dislocation.