Identifier

etd-08302011-110325

Degree

Master of Science (MS)

Department

Geology and Geophysics

Document Type

Thesis

Abstract

The “V-line” levee, located in Marrero, LA, has a crack along its crest, measuring approximately 100 meters in length, 30 centimeters in depth, and 30 centimeters in width. This crack is a sign of levee instability. Seismic shear wave, CPT, and laboratory shear strength data were collected and processed to identify the cause of the instability. A zone of low seismic shear wave velocity was interpreted approximately 3 meters deep from the berm of the levee. Because of the large spacing between laboratory shear strength test sampling and CPT sites, a similar zone of low shear strength was not found in the CPT and laboratory shear strength data. High contents of peat and organic clay were interpreted within and beneath the levee fill using CPT data; the location of the highest contents of organic clay and peat correspond to the location of the levee instability. Organic material tends to have a lower shear strength and higher water retention which can cause lower shear strengths and higher shear stress after heavy rainfall. Based on the location of the crack at the crest of the levee and the zone of low seismic shear wave velocity, it is likely that the crack at the crest of the levee is a precursor to slope base failure.

Date

2011

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Lorenzo, Juan

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