Development of a generalised formula for dynamic active earth pressure

The Mononobe-Okabe method is widely used in practice to estimate dynamic active earth pressure. The method, derived from Coulomb's theory, cannot account for the effect of cohesion and hence cannot be used for a cohesive backfill. In addition, the effect of wall adhesion and external load cannot be taken into account. This paper develops a new general formula for dynamic active earth pressure on a yielding wall. The strength of the formula is that it can take into account the effects of cohesion, wall adhesion and external load on dynamic active pressure, while remaining simple in form. The dynamic earth pressures calculated by the proposed formula, the Mononobe-Okabe method, and the graphical solution are compared for validation. The comparisons demonstrate the accuracy of the proposed formula. The formula is used in a parametric study to investigate the influence of cohesion, wall adhesion and external load. This study shows that the additional terms can significantly influence the calculated dynamic active earth pressure.