SIMPLE DIRECT SHEAR TESTING TECHNIQUES FOR ROCK SLOPE STABILITY ANALYSIS

In order to determine the shear strength parameters of cohesion and friction angle for the Price Formation of Mississippian age in Montgomery County, Virginia, simple unconventional direct shear tests were performed on both natural and saw-cut rock sample surfaces. Three structural domains were identified within a road cut along Stroubles Creek Road where rock slope stability analyses were to be performed in the Price Formation. Low normal stresses were found to exist along the discontinuities of interest allowing for direct shear testing to be performed using a machine normally used for soil testing. The natural shear test surfaces produced higher friction angle results compared to the saw-cut surfaces, as expected. The saw-cut surfaces were expected to provide lower-limit values similar to residual shear strengths. The test results were then used to perform kinematic stereonet analyses followed by safety factor calculations, together providing an overall evaluation of rock slope stability conditions adjacent to Stroubles Creek.