Surcharge Lateral Pressure on a Wall from a Line Load (Boussinesq)
The bulge of lateral pressure a concentrated surface load (a footing, wheel line, or crane outrigger set back from a wall) puts on it - which the uniform Ka q surcharge never captures: the NAVFAC DM-7.2 modified-Boussinesq sigma_h = (0.203 qL/H) n/(0.16 + n^2)^2 for m <= 0.4, doubled for a rigid non-deflecting wall (m = x/H, n = z/H). A 1,000 lb/ft line 4 ft back from a 10 ft wall peaks near 97 psf at shallow depth; set it farther back and it pushes less and deeper. Line load, single depth. A design aid; the geotechnical engineer of record governs.
Formula and source
m = x/H, n = z/H; m <= 0.4: sigma_h = (0.203 qL/H) n/(0.16 + n^2)^2; m > 0.4: sigma_h = (1.28 qL/H)(m^2 n)/(m^2 + n^2)^2.
The NAVFAC DM-7.2 modified-Boussinesq line-load lateral pressure on a rigid wall, the doubled elastic Boussinesq solution for an unyielding wall, by name.
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