 According to this Engineer Manual, an appropriate SMF value allows calculation of greater-than-active earth pressures using Coulomb's active force equation.Assuming an average SMF value equal to 2/3 along Coulomb's failure surface, it has been shown that for purely frictional soils the derived coefficient value of earth pressure matches quite well with the respective one derived from Jaky's formula_8 equation.In the solution proposed by Pantelidis, the SMF factor is the formula_96 ratio and what has been foreseen by EM1110-2-2502, it can be calculated exactly.