1. Hydro-Mechanical Properties and Stability Analysis of Four Landslide-Prone Hillslopes in Western North Carolina 30 October 2013 York W. Lewis 1, Alexandra Wayllace 1, Jonathan W. Godt 2, Richard M. Wooten 3, and Ning Lu 1 1 Colorado School of Mines 2 U.S. Geological Survey 3 North Carolina Geological Survey

2. Objectives Photos courtesy of NC Geological Survey

3. Site Locations Poplar CoveMooney GapBent Creek Maps courtesy of NC Geological Survey

4. Typical Soil Horizon Thicknesses O A B C 30 cm 60 cm 20 cm Classification: Silty Sands (SM), Silty Clays (SC)

5. Laboratory Tests

6. Test Results

7. Infinite-Slope Stability Analysis ɸ’ = Effective friction angle (degrees) β = Slope angle (degrees) c’ = Effective cohesion (kPa)  s = Suction stress (kPa)  Unit Weight (kN/m 3 ) z = Vertical depth (m) (Lu and Godt, WRR, 2008) SampleIn situ Factor of Safety Pore Water Pressure (kPa) for FOS = 1 MG1TP1, 115-125cm2.116.7 MG4Tp1, 70-80 cm2.347.7 PC2TP1, 50-65 cm2.728.15 BC1TP1, 100-105 cm2.1413.5

8. Conclusions