Feasibility Study of High-Performance Cut-off Walls for Levees in Seismic Regions: Dynamic Wall Analyses and Ductile Slurry Development

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The vast majority of U.S. river cities, now growing at increasing rates, are protected from flooding by earthen levees that are at risk from many sources of failure including seepage (both underseepage and through seepage), erosion and instability due to seismic loading. This grant provides funding to develop a novel type of slurry cut-off wall for levees that possesses multiple risk mitigation, including seepage resistance, high seismic resistance, constructability, and sustainable fabrication. The project aims at establishing the feasibility of such a cut-off wall through a combination of advanced materials design and non-linear dynamic numerical simulation of failure resistance against seismic loading. The cement and bentonite based material reinforced with nano/micro fibers will be designed using a micromechanics composite design methodology combined with numerical analyses of cut-off walls under seismic loading. To confirm the expected benefits, the project will include finite-element numerical analyses of levees and embankments with cut-off walls to understand the mechanical behavior of these slurry cut-off walls under seismic loading, as well as the soil-cut-off wall interaction. The results of this research will directly impact the design of vertical cut-off walls for levees in seismic regions, providing a safer, more efficient and sustainable alternative. The coupled material tailoring, mechanical and transport property testing, and soil-structure analyses represent a novel departure from past practice and provide an intellectual platform to attain significantly enhanced safety for U.S. river cities. This interdisciplinary project is expected to bring about new approaches to addressing the performance of broad geotechnical infrastructure systems beyond levees, including e.g. piles, below grade pipes and underground construction that have common features of soil/structure/materials interactions and are often subjected to large imposed deformation and water seepage.