CHAPTER 5
FOUNDATION ANALYSES
Section I. Bearing Capacity of Wall Foundations
5-1. Analysis Principles and Methods.
a. EM 1110-2-1903. A discussion of the principles and methods involved
in analyzing bearing capacity is contained in EM 1110-2-1903. The manual concludes that Terzaghi's general bearing capacity equation, q = CN + wz N
C 9
+ WbNw , is preferred. However, the manual does not address modifying the
general equation for effects of embedment, inclined loads, sloping bases,
passive-type wedges with sloping surfaces, overburden pressure, and eccentric
loads (moment-induced stresses), all of which are needed for computing the
bearing capacity of retaining and flood walls. The computer program CBEAR
(Appendix 0) can assist in these computations.
b. Mode of Failure. The mode of failure depends on the relative com-
pressibility of the soil, loading conditions, and geometric considerations
(Vesic 1975). This manual is restricted to general shear failure of shallow
strip foundations, i.e., those whose widths are greater than their embedment.
A general shear failure normally exists for dense sand and stiff clay. How-
ever, for loose sand and soft clay, which may occur more frequently for flood
walls constructed in a flood plain, the bearing capacity should be computed
based upon local shear conditions (Vesic 1975).
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