2020 Virtual undergraduate Research symposium
Effects of Curvilinear Failure Envelope on Slope Stability
* THIRD PLACE BEST IN SHOW *
PROJECT NUMBER: 39
AUTHOR: Alexander Wood, Civil and Environmental Engineering | MENTOR: Alexandra Wayllace, Civil and Environmental Engineering
ABSTRACT
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Traditional geotechnical engineering calculates soils strength using a linear failure envelope: Mohr-Coulomb. However, there is ample evidence that the relationship between normal stress and shear strength for some soils, is non-linear. This poster presents further evidence supporting nonlinear behavior of a soil failure envelope and an analysis of slope stability with the nonlinearity of a failure envelope considered compared with the traditional, linear method. Shear strength properties of saturated, undisturbed soil samples were measured through direct shear tests, which demonstrated the nonlinear relationship, especially at low normal stresses. A series of slope stability analyses were performed, comparing the use of linear and non-linear failure envelopes; the variables that changed were soil type, slope angle, water table position, and depth to a strong soil layer. For two different soils, numerical modeling was performed using failure envelopes based on published data. A curvilinear failure envelope generally causes a decrease in factor of safety (FS), showing a significantly greater decrease for shallow failures, the difference in FS between linear and non-linear failure envelope analyses decreases as the slope angle increases, and there is no apparent change to the difference in FS between the linear and nonlinear analyses when incorporating a water table.
VISUAL PRESENTATION
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AUTHOR BIOGRAPHY
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Alex is a junior studying civil engineering with a minor in public affairs and has been doing research in the civil and environmental engineering department. His research has been on the effect of using a curvilinear failure envelope when compared with the traditional Mohr-Coulomb linear relationship in slope stability. Alex’s primary research has been in illustrating the curvilinear relationship in the failure envelope of a soil through experimental testing and computer slope stability analyses that compare the factor of safety between linear and curvilinear failure envelopes. He would like to see further analysis of slope stability using curvilinear failure envelopes and investigation into the impact of curvilinear envelopes on shallow foundations.
Good paper, very clear, not too wordy (though I recommend against whole paragraphs in poster or slide papers). Motivation for the research was clear, and the conclusions seemed sound, though maybe a little overgeneralized. I was not familiar with the term “failure envelope,” but it seemed clear enough. 1 or 2 of the nonlinear fits did not look so close at the high end, and I thought that bore comment (incidentally, watch those significant digits).