Taylor’s Slope Stability Charts Revisited

Two design charts for computing the safety factor of soil slopes are presented here. The first one is for an undrained (ϕu=0) soil slope, similar to the one proposed by Taylor, but with significant differences. Taylor’s work is based on three types of failure circles: toe circle, slope circle, and midpoint circle. It appears that there can also be compound circles that are made of two circular arcs separated by a straight line at the interface with the stiff stratum. These are incorporated in the proposed design chart. The second chart is for drained (c′-ϕ′) soil slope that enables the users to compute the safety factor of the slope without any iterative procedures that are required with the Taylor’s chart. In c′-ϕ′ soils, Taylor assumed that the failure occurs along toe circles. The analysis presented herein shows that when the slope is very shallow, it is possible to have midpoint circles. Both charts are quite simple and straightforward to use in engineering analysis of homogeneous slopes. Numerical examples are presented to illustrate the use of the two design charts.