ABSTRACT
If the slope angle {3, height of embankment H, the effective unit weight of material ~ angle of internal friction l/J', and unit cohesion c' are known, the factor of safety may be determined. In order to make unnecessary the more or less tedious stability determinations, Taylor (1937) conceived the idea of analyzing the stability of a large number of slopes through a wide range of slope angles and angles of internal friction, and then representing the results by an abstract number which he called the "stability number". This number is designated as N
s • The expression used is
From this the factor of safety with respect to cohesion may be expressed as
(10.23)
Taylor published his results in the form of curves which give the relationship between N s
and the slope angles /3 for various values of l/I as shown in Fig. 10.16. These curves are for circles passing through the toe, although for values of {3less than 53°, it has been found that the most dangerous circle passes below the toe. However, these curves may be used without serious error for slopes. down to {3 = 14°. The stability numbers are obtained for factors of safety with respect to cohesion by keeping the factor of safety with respect to friction (Ft/J) equal to unity.
