Doctor of Philosophy (PhD)
Civil and Environmental Engineering
Continuously-connected, articulated revetment systems have potential to decrease the weight of armor cover in resisting wave attack, compared to traditional designs. Modes of instability for sloping revetments include uplift, sliding, and toe roll-up. Design methods are summarized by McDonnell (1998), Pilarczyk (1998), and Herbich (1999). Russo (2003) conducted a field prototype scale investigation on performance of Articulated Concrete Mattresses (ACMs) in coastal Louisiana, which demonstrated this structure’s ability to resist a range of wave loading conditions, and inspired scoping of further research to quantify structure performance beyond known limits. Present research expanded earlier works by examining fundamental physical processes of wave loading near the theoretical threshold of structure incipient motion. The motivation for further investigation and modeling modes of failure is to: (1) demonstrate a method to support the design selection process, (2) optimize revetment dimensions when articulated block is considered the most appropriate application, and (3) meet earthen slope protection requirements with relatively low ground pressures exerted by the armor layer for use in soft soil conditions. A new structure performance metric is derived as the physically dimensionless “hydromechanic potential,” which is used to quantify structure movement as an interconnected system under wave attack. Research involved using a spectral hydromechanics analytical approach, with instrumented physical model results, to demonstrate a capability for constraining uncertainty on the behavior of revetments in specified conditions. Physical modeling was conducted based on dimensional analysis and similitude criteria. Physical modeling and spectral analysis were based on principles of hydrodynamics and structure mechanics of articulated revetment system configurations at incipient motion under irregular wave conditions. Theoretical equilibrium exists when destabilizing wave loading forces are in balance with restoring gravitational forces of the structure. Tests of prior works, conducted through traditional methods, were generally able to measure structure performance under wave attack to between 3.7 and 8 of the ratio of destabilizing-to-restoring forces. Despite being the best available physical data measurable to-date, Herbich (1999) characterized structure performance in this range for design as “doubtful”. Results of this dissertation research indicated that a new lower limit is detectable at the threshold of equilibrium based on hydromechanic potential.
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Russo, Edmond Joseph, "Stability of Articulated Revetments Against Wave Attack on Shallow Soft Soil Slopes" (2009). LSU Doctoral Dissertations. 3003.