Semester

Fall

Date of Graduation

2012

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

John D Quaranta

Committee Co-Chair

Vladislav Kecojevic

Committee Member

Hema Siriwardane

Abstract

This report presents the findings of geotechnical testing on two material types retrieved from a surface mine site in Logan County, West Virginia, and investigates geomorphic landform design as an alternative in lieu of typical valley fill design and approximate original contour (AOC) surface mine reclamation design. Laboratory testing was carried out according to ASTM standard test methods. The scope of the testing performed involved grain size distribution analysis, hydrometer analysis, saturated shear strength testing under an insitu consolidation load, Atterberg limits including plastic and liquid limits, compaction at three predetermined compaction energies, and rigid wall permeameter hydraulic conductivity testing. Data was evaluated and analyzed to find to what degree the material particles moved under certain hydraulic gradients and if the particle movement affected the shear strength of the samples. The objectives of the testing were to understand the movement and behavior of small diameter soil particles at a valley fill and use the strength values as input parameters into several modules of GeoStudio(TM) for numerical slope stability modeling.;The numerical modeling involved geomorphic design for a proposed valley fill in southern West Virginia using commercial software following the Geofluv RTM method. A comprehensive seepage and slope stability analysis was then developed using the SEEP/W, SIGMA/W, and SLOPE/W modules of GeoStudio2007(TM) for assessing the groundwater flow characteristics of the blasted, unweathered sandstone fill, an insitu load calculation, and the resultant limit equilibrium analysis of slope stability (static factor of safety). These analyses were performed for both the AOC and geomorphic fill designs.;The cumulative analysis for the geomorphic valley fill alternative design yielded the highest factors of safety. Most cases produced factors of safety over 2.0. The failure locations were sought out to produce the lowest factors of safety for the structure. None of the factors of safety modeled yielded factors of safety under 1.0 for the geomorphic design. The results imply that the geomorphic design can remain very stable when a range of hydrologic conditions and geometries are applied.;Regulations require that reclaimed slope factors of safety must remain above 1.5. The analyses performed showed that the AOC valley fill design could withstand insitu loads and produced slope angles under most hydrologic conditions analyzed. Elevated pore pressures tended to result at the toe of the slope, and decreased the factor of safety. The most critical scenario was a fully saturated toe which yielded a factor of safety of 0.50.;If particle transport can occur and alter toe pore pressures, it is possible that some small slope failure may occur. The gradations that were found for the unweathered well graded sand with silt fill material showed that particle transport would not be a significant concern. The gradations that were found for the range of cases analyzed for the unweathered well graded sand with silt showed aggregation phenomena which could have implications on the long term stability of the earthen structures.

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