The contributory area approach used for the static stability analysis of segmental retaining
walls is extended to the dynamic loading case. In thismethod the reinforcement
layers aremodelled as tie-backswith the dynamic tensile force, Fdyn , in each layer equal
to the dynamic earth pressure integrated over the contributory area, Sv , at the back of
the facing column plus the corresponding wall inertial force increment, khΔWw . The
contributory area for the topmost reinforcement layer is taken from the top of the crest
to mid-elevation between the first and second reinforcement layers from the crest. For
the simple geometry illustrated in Figure 12, the dynamic factor of safety, FSos , against
over-stressing of a reinforcement layer at depth z below the crest of the wall is given
by