Upper Bound of Seismic Active Earth Pressure on Gravity Retaining Wall with Limited Backfill Width

The failure mechanisms of backfill with limited width that is subjected to a co-application of earthquake force and surcharge formed by single and double wedges, respectively, were introduced to address the active earth pressure acting on gravity walls. An analytic model that is applicable to general cases of tilt walls with frictional backs and inclined ground surfaces was established by incorporating the quasi-static Mononobe-Okabe method and upper bound limit analysis. The reasonability and effectiveness of this technique were verified and supported by a comparison with results from reported laboratory model tests. A sample case analysis revealed a nonlinear distribution of active earth pressure on a gravity wall with limited backfill width. Coulomb's solution and three other published methods tended to overestimate the earth pressure measured in the laboratory more significantly than the proposed method did when the width of the backfill was reduced to a critical threshold. The superiority of this suggested technique increased with the shrinkage of backfill width. Moreover, the ascending horizon seismic coefficient k and surcharge q mobilized an increasing active thrust on the wall while easing and enlarging the crack angle of the slip surface, respectively.