Location

Portland, OR

Start Date

28-6-2016 1:30 PM

DOI

doi:10.15142/T3370628160853

Description

A 0.91-m (3-ft) high, homogeneous, silty clay embankment was tested to investigate erosion processes occurring during failure by internal erosion. The embankment was constructed in a 3.79-m (12.44-ft) wide test flume equipped with a clear acrylic viewing window at the abutment where failure was initiated. Failure was initiated at mid-height when an embedded 12-mm (½-inch) diameter rebar was removed from the embankment. The test lasted approximately 48 minutes, and during that time the erosion pipe enlarged dramatically. The test was stopped just before the collapse of the soil bridge over the enlarged pipe.

Erosion was visually monitored during the test with video cameras and arrays of still cameras imaging the top of the embankment and the visible abutment. Still photos provided time-lapse imagery and were also used to develop a time-lapse 3D photogrammetric model of the developing erosion channel with estimated areal extents of erosion. Water levels and flow rates were also measured during the test, and data were recorded from an array of geophysical sensors installed on the embankment crest and downstream surface. The embankment materials were characterized before and during construction with in situ measurements of water content, dry density, and erodibility. Visual observations and recorded imagery showed complex flow structures and erosion patterns that are typically not incorporated into current idealized numerical simulation models of the breach erosion process.

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Jun 28th, 1:30 PM

Visual and Photogrammetric Observations of an Internal Erosion Failure

Portland, OR

A 0.91-m (3-ft) high, homogeneous, silty clay embankment was tested to investigate erosion processes occurring during failure by internal erosion. The embankment was constructed in a 3.79-m (12.44-ft) wide test flume equipped with a clear acrylic viewing window at the abutment where failure was initiated. Failure was initiated at mid-height when an embedded 12-mm (½-inch) diameter rebar was removed from the embankment. The test lasted approximately 48 minutes, and during that time the erosion pipe enlarged dramatically. The test was stopped just before the collapse of the soil bridge over the enlarged pipe.

Erosion was visually monitored during the test with video cameras and arrays of still cameras imaging the top of the embankment and the visible abutment. Still photos provided time-lapse imagery and were also used to develop a time-lapse 3D photogrammetric model of the developing erosion channel with estimated areal extents of erosion. Water levels and flow rates were also measured during the test, and data were recorded from an array of geophysical sensors installed on the embankment crest and downstream surface. The embankment materials were characterized before and during construction with in situ measurements of water content, dry density, and erodibility. Visual observations and recorded imagery showed complex flow structures and erosion patterns that are typically not incorporated into current idealized numerical simulation models of the breach erosion process.