Influence of Soil Suction and Seismic Excitation on Active Earth Pressure

Earthquake-induced slope failures are common occurrences in engineering practice. The rigid gravity retaining wall remains an effective technique in maintaining the slope stability. Based on the pseudo-dynamic approach, the seismic response of unsaturated backfills is studied using the kinematic limit analysis method. To formulate the energy balance equation, a horizontal slice method is proposed. The work rates of unsaturated soil gravity, seismic inertia force and damping force that are all characterized with conspicuous nonlinear distribution characteristics are computed using this method. A series of parametric analysis is conducted regarding the influences of soil suction and seismic excitations on the earth pressure estimations. The results show that the suction effect relates not only to the soil types but also the seismic excitations. The earth pressure is overestimated by 15%-32% when soil suction is not considered in the analyses. For hard backfills, the peak active earth pressure increases slightly and moves towards the negative direction.