Geosynthetic landfill cap stability: comparison of limit equilibrium, computational limit analysis and finite-element analyses

摘要

The stability of the veneer cover soil (landfill cap) is an important issue in landfillndesign. Incorrect design of the landfill cap can lead to failure, which may result in the veneerncover soil sliding on an underlying geosynthetic layer, or in tension failure of the geosyntheticnitself. Previous limit equilibrium (LE) analyses of veneer cover layer stability presented in thenliterature have generally considered whole-slope failure. In this paper, modified LE equations arenproposed that (a) encompass more critical cases of localised slope failure for specific cases, andn(b) are calibrated against two other methods: 2-D computational limit analysis (CLA) usingnLimitState:GEO and 2-D elasto-plastic finite-element (FE) analysis using PLAXIS. The scenariosnexamined encompass a cover of uniform thickness, a buttressed cover, a cover of tapered thickness,nthe effects of seepage forces, and the effects of construction equipment. It is shown that the LEnmethod provides a reasonable estimate of veneer cover layer stability for most cases examined,nalthough it is in general non-conservative, relative to the CLA and FE analyses. Local failure wasnfound to be critical in the case of the construction equipment, buttress and horizontal seepagenscenarios. In the latter case the LE equations previously presented in the literature significantlynoverestimate stability compared with the LE, CLA and FE analyses considered in this paper.