FACTOR OF SAFETY Determining slope stability in Holtwood, PA in the aftermath of Hurricane Sandy...

of 3 /3
FACTOR OF SAFETY Determining slope stability in Holtwood, PA in the aftermath of Hurricane Sandy Kristina Lofman November 27, 2012 EPS 109

Embed Size (px)

Transcript of FACTOR OF SAFETY Determining slope stability in Holtwood, PA in the aftermath of Hurricane Sandy...

PowerPoint Presentation

FACTOR OF SAFETYDetermining slope stability in Holtwood, PA in the aftermath of Hurricane Sandy

Kristina LofmanNovember 27, 2012EPS 109

S = Shear resistance (strength)T = Shear stress

Ca = apparent cohesion (kPa)f = unit weight of soil and field moisture (kN/m3)z = vertical soil depth (soil mantle thickness*cos) = slope angle (degrees) = internal angle of friction (degrees)u = pore water pressure at the failure surface (kPa)

At failure, S = T

Sidle, R. C., & Swanston, D. N. (May 01, 1982). Analysis of a small debris slide in coastal Alaska. Canadian Geotechnical Journal, 19, 2, 167-174. MECHANICS OF FAILURE FACTOR OF SAFETYPore water pressure is the only value that changes:

Increasing precipitation

Increasing pore water pressure

Decreasing shear resistance

To calculate FS for spatial data of slopes, run projectcode.Lofman.m using slope data (clip_output.txt)Black: minimal slope

Yellow: stable

Red (maroon):unstable