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Fig. E-5.
Unsuitable convex failure surface generated by a negative
deflection angle
3.
Δθmax is limited to an angle less than 45E as larger deflection angles will lead to a poor
approximation of a circular surface (see Fig. E.6).
4.
If Δθmin greater than 45E, the lower angular limit is changed to θ1, similar to case 2 above,
and the search is repeated with a new initial segment for an acceptable Δθmin value.
Fig. E-6.
Maximum limit for deflection angle for generation of suitable
circular surfaces
5.
An overturned shear surface may be generated if the center of the circle is below the
elevation of the termination range, as shown in Figure E.7. This problem is avoided by
reducing Δθmax such that a circle center corresponding to the left termination limit is at least
T/2 above the elevation of the termination range (Fig. E.8). The overall effect of this
feature is to move the left termination limit to the right.
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