A New Pseudo-dynamic Approach for Seismic Active Soil Thrust

A critical review of the existing pseudo-dynamic approach is provided and a new pseudo-dynamic approach is proposed based on a visco-elastic behavior of backfill overlying rigid bedrock subjected to harmonic horizontal acceleration. Considering a planar failure surface, closed form expressions for seismic active soil thrust, soil pressure distribution and overturning moment are obtained. The results of this study indicate that the existing pseudo-dynamic method can strongly underestimate the soil active thrust especially close to the fundamental frequency of the backfill, where the soil response is more sensitive to the damping ratio. The acting point of the total seismic active thrust is always found to be higher than that predicted by the traditional pseudo-dynamic approach. The effect of the shear resistance angle and wall friction angle on the acting point increases as the amplitude of the base acceleration increases, whereas their effect is generally small far from the natural frequencies of the backfill.