where P
p
=passive resistance per unit width of pile (lb/ft or kN/m).
k
p
=passive earth pressure coefficient [k
p
=tan
2
(45°+1
/
2f′)], dimensionless.
f′=effective friction angle of the cohesionless soil. The effective friction angle could be
determined from drained direct shear tests or from correlations such as shown in
Figs. 3.12 to 3.14.
g
t
=total unit weight of the soil (pcf or kN/m3
). The buoyant unit weight is required if the
pile is below the groundwater table.
H =length of the pile that is laterally pushed into the uniform cohesionless soil and subjects
the pile to passive pressure (ft or m). Because of restrictions on lateral deflections, typically only the upper few feet of the pile will be subjected to passive pressure.