NEESR: Performance Based Seismic Design of Geomembrane Liner Systems for Waste Containment

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This award will provide engineers with an improved ability to determine whether or not a modern geomembrane liner waste containment system can maintain its integrity when subjected to a strong earthquake. Current practice for evaluating the ability of waste containment systems to withstand earthquake loading employs an empirical index of performance rather than direct calculation of the loads (stresses and strains) on the geomembrane liner. This award will use centrifuge model testing to evaluate input parameters essential to direct calculation of liner stresses and strains and to validate a numerical model to evaluate these stresses and strains. Validation of the model will include validation of the influence of stress (or strain) concentrations due to seams, patches, and anchor trenches on liner performance. Data from this project will be archived and made available to the public through the NEES Project Warehouse/data repository (http://www.nees.org).This award offers the promise of a new paradigm for seismic design of waste containment systems, transforming current engineering practice for geomembrane liner system seismic design from an empirical process that depends upon an unreliable index of performance to a performance-based seismic design procedure in which the seismic loads on the geomembrane are directly evaluated. The project may also have a transformative impact on landfill liner construction quality assurance (CQA) practices, as experimental verification of strain concentration factors for seams, patches, and anchor trenches in geomembranes should lead to new guidelines on where it is appropriate to cut seam samples for CQA testing (e.g. never at the top of a slope or near an anchor trench) and perhaps on the frequency of such testing. By facilitating more rational performance-based seismic design and CQA, the project should enhance environmental protection and facilitate the development of more effective design and construction practices for waste containment systems subject to earthquake loading. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).