TM 5-818-1 / AFM 88-3, Chap. 7
earth pressures (fig 14-8). Generally, a linear variation
Design procedures for retaining walls.
in earth pressure coefficients with depth may be
a. Criteria forselecting earth pressures.
assumed between the sections of wall.
(1) The equivalent fluid method should be
(4) Consider passive pressures in the
used for estimating active earth pressures on retaining
design if applied loads force the structure to move
structures up to 20 feet high, with the addition to earth
against the soil. Passive pressures in front of retaining
pressures resulting from backfill compaction (fig 14-8).
walls are partially effective in resisting horizontal sliding.
(2) For walls higher than 20 feet, charts,
b. Overturning. Calculate the factor of safety,
equations, or graphical solutions should be used for
FS, against overturning, defined as the ratio of resisting
computing lateral earth pressures, with the addition of
moments to the overturning moments. Calculate the
earth pressures resulting from backfill compaction.
resultant force using load diagrams shown in figure 14-1,
(3) Use at-rest pressures for rigid retaining
as well as other loadings that may be applicable. Use
structures resting on rock or batter piles.
only half of the ultimate passive resistance in calculating
cantilever walls founded on rock or restrained from
the safety factor. The resultant of all forces acting on the
lateral movement for at-rest pressures near the base of
retaining wall should fall within the middle third to provide
the wall, active pressures along the upper portions of the
a safety factor with respect to overturning equal to or
wall, and compaction-induced earth pressures from the
greater than 1.5.
top to the depth at which they no longer increase lateral
(Courtesy of R. B. Peck, W. E. Hanson, and T. H.
Thornburn, Foundation Engineering, 1974, p 309. Reprinted
by permission of John Wiley & Sons. Inc., New York.)14-5
Figure 14-4. Active and passive earth pressure coefficients according to Coulomb theory.