5-9. Combination of Factors. As dis

5-9. Combination of Factors. As discussed in the CBEAR user's guide (Mosher
and Pace 1982)' the correction factors for the load inclination, base tilt, and
ground slope and the adjustment for the load eccentricity should only be used
in unison when all of these factors tend to produce failure in the same
direction.
5-10. Example. Example problems using the general bearing capacity equation
are presented in Appendix N.
Section 11. Other Considerations
5-11. Settlement.
a. EM 1110-2-1904. A discussion on the various factors involved in the
settlement of a structure, on methods for estimating settlements, and on the
limitations in the accuracy of conducting settlement analyses from laboratory
tests is contained in EM 1110-2-1904. The principles and methods presented are
applicable to a majority of civil works projects. Additional information for
unique or special projects can be obtained from various texts on soil
mechanics. The computer program CSETT (Appendix 0) can assist in performing a
settlement analysis.
b. Allowable Settlement. The maximum value of angular distortion
(settlement/length of structure) which can be tolerated without cracking of
reinforced concrete retaining walls is 0.002 to 0.003 radian (Duncan and
Buchignani 1976).
5-12. Deep-Seated Slidinq. A deep-seated sliding analysis should be performed
to check for sliding within weak layers which may exist beneath structures.
The analysis should be in accordance with procedures outlined in
paragraph 4-16. Active and passive wedges should be located a sufficient dis-
tance apart to allow a rotational slip surface to develop. Generally, a slip
plane inscribed in an arc with a radius equal to the height of the active wedge
will comply with this requirement (Figures 5-2 and 5-3). When the wall is
resting on thick strata of weak soils, shallow shear failure should be investigated. This may be assumed to occur below the base of the retaining or
flood wall along a cylindrical surface passing through the heel (Figure 5-4).
The minimum factor of safety, which must not be less than 1.5, is determined by
trial and error by changing the center of the trial circle