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Insights from laboratory experiments on the failure of earthen embankments at bridge-waterway abutments




Ettema, R., author
Ng, K. W., author
Colorado State University. Department of Engineering, publisher

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Failure of compacted, earthfill embankments during breaching combines geotechnical and hydraulic processes that interact to erode the compacted earthfill. Our paper offers insights regarding these processes as observed during a series of laboratory flume experiments conducted to investigate the effect of soil strength on scour depth at abutments formed of erodible, compacted earthen approach embankment. The length scale of the model abutments was 1:30. We highlight the challenges in conducting laboratory experiments involving erodible model abutments. The challenges, or difficulties, include attaining scale-reduced shear strengths, controlling and verifying the soil compaction, and quantifying the in-situ shear strength of both non-cohesive and cohesive model soils. We addressed these difficulties through a sequence of soil tests designed to relate model soil strength to laboratory compaction, using hand-held devices to check soil strengths in the flume experiments. Our paper explains the successes and unresolved issues relating to the shear strength of model soils used in flume studies of embankment breaching. Additionally, our paper illustrates the importance of large-scale turbulence structures formed at the breach entrance in shaping the breach, and discusses the geotechnical manner whereby breaches widen.


Presented at the Protections 2016: 2nd international seminar on dam protection against overtopping: concrete dams, embankment dams, levees, tailings dams held on 7th-9th September, 2016, at Colorado State University in Fort Collins, Colorado, USA. The increasing demand for dam and levee safety and flood protection has motivated new research and advancements and a greater need for cost-effective measures in overtopping protection as a solution for overtopping concerns at levees and dams. This seminar will bring together leading experts from practice, research, development, and implementation for two days of knowledge exchange followed by a technical tour of the Colorado State University Hydraulic Laboratory with overtopping flume and wave simulator. This seminar will focus on: Critical issues related to levees and dams; New developments and advanced tools; Overtopping protection systems; System design and performance; Applications and innovative solutions; Case histories of overtopping events; Physical modeling techniques and recent studies; and Numerical modeling methods.
Includes bibliographical references.

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earthen embankments


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