geotech (version 1.0)

slopeStability: Slope Stability

Description

These functions are used to determine the factor of safety against shear failure on slopes using infinite slope analyses (FSinf) or planar failure analyses (FSplanar).

Usage

FSinf(c, phi, gamma, gammaW = NA, alpha, D, zw, metric)
FSplanar(c, phi, alpha, L, W, u)

Arguments

c

soil cohesion

phi

soil friction angle (degrees)

gamma

soil unit weight

gammaW

unit weight of water (default = 62.4 pcf for English units; 9.81 kN/m^3 for metric units)

alpha

slope angle (angle of failure plane) for infinite slope analysis; angle of failure plane for planar failure analysis (deg)

D

depth to failure plane

zw

distance of groundwater table above failure plane (use 0 for a dry slope and D for a submerged slope with parallel seepage)

metric

logical variable: TRUE (for metric units: kN/m^3) or FALSE (for English units: pcf) [this is needed if gammaW is unspecified]

L

length of failure plane (planar failure analysis)

W

weight of slope per unit width (planar failure analysis)

u

average pressure head on the failure plane (planar failure analysis)

Details

• The assumptions of infinite slope analyses include (Coduto et al., 2011):
  1. The slope face is planar and of infinite extent.
  2. The failure surface is parallel to the slope face.
  3. Vertical columns of equal dimensions through the slope are identical.

• For planar failure analysis, the angle of the failure plane is generally not equal to the failure angle. The geometry of the failure wedge is specified using its weight, W.
• Either English or metric units can be used, but must be consistent.

References

Coduto, D.P., Yeung, M.R., and Kitch, W.A. (2011). Geotechnical Engineering: Principles and Practices, Second Edition. Pearson: Upper Saddle River, N.J.