Date of Graduation

2014

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

John D Quaranta

Abstract

This report presents the findings of numerical modeling analyses on rock cut slopes sites in Hardy County (U.S. Route 48) and Raleigh County (U.S. Route 121), West Virginia, and investigates the feasibility of design alternation in lieu of current cut slope practices performed by West Virginia Department of Highways. The scope of this research was to provide a new design process (i.e. flow charts and design charts) for rock cut slope design with respect to geotechnical bench reduction with the aid of numerical modeling.;The numerical modeling involved evaluations of current cut slopes and the investigation of design alternatives in various locations in West Virginia. The modeling software suite used for this analysis was SoilVision Systems(TM). The comprehensive modeling entailed slope stability analysis within the program module SVSlopeRTM. Various failure criterion methods were assessed, in addition to multiple stability analysis approaches. It was found that the Hoek-Brown failure criterion provides the most accurate representation of fractured rock behavior, due to the consideration of fracture assessment on the exposed slope face. The stability analysis method used in the calculations was the General Limit Equilibrium.;The bench reduction process conducted on U.S. Route 121 was performed in a friable, less desirable geological composition. The analysis yielded the elimination of one geotechnical bench during the redesign trials which lead to the increase in slope stability in three of the four redesign cases. Trial three of the reduction process showed an increase in stability by approximately 24%. This would not only allow for a greater structural integrity is will allow for lower excavation quantities to be left in place, lowering the overall construction cost.;The bench reduction on U.S. Route 48 encountered hard competent rock material. The analysis illustrated that geotechnical bench elimination possible. The initial assessment on this route illustrate an over designed slope with bench implementation. One of the bench reductions performed lowered the factor of safety from the initial evaluation; however the calculated stability results exceeded the minimum requirement of 1.25 by approximately 20%. This result deemed the bench reduction process a success for this case study.;The cumulative analysis of the alternative design approach yielded factors of safety that met or exceeded the minimum requirement of 1.25 stated with WVDOH regulations. The predicted failure locations were shallow non-circular failures near the surface of the back slopes. The results showed that alternative designs with regards to continuous vertical heights exceeding 50 vertical feet are plausible within the geology formations in West Virginia. It is possible that some small slope failure may occur with the weathering of exposed rock, it is believed that this material will be captured mid-slope on the geotechnical benches given the intended use.

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