The following conclusions may be drawn from this paper:
1. Amplification of motion in the backfill plays an important role with
regard to the permanent displacement of the wall when the ratio of the
dominant frequency of ground motion to the fundamental frequency of
the backfill is greater than 0.3.
2. For purposes of design the Richards-Elms procedure may be modified
simply to take the effects of ground motion amplification on permanent
wall displacement into account.
3. Earthquake loading causes stress redistribution such that, following
an earthquake, the residual force on the wall may be as much as 30%
greater than the static active force.