Seismic Analysis of Lateral Earth Pressure and Retaining Walls

Eart pressure problems are encountered
in retaining walls, bulkheads,
sheeting and bracing in cuts,culverts,
tunnels, and cofferdams. In many cases,
the lateral pressure is determined by
use of classical earth pressure theories,
such as Coulomb's, where the equilibrium
conditions of a failure wedge
of soil is considered.
Excessive dynamic lateral earth
pressure on retaining structures resulting
from earthquake has caused several
major damages in the past. The increase
of lateral earth pressure during earthquakes
induces sliding and/or tilting
to the retaining structures. The majority
of case histories of failures reported
in the literature until now concern
waterfront strustures such as quay walls
and bridge abutments.
In this parer the major aspects of
this problem, such as, variation of
earth pressure due earthquake motion,
point of application of the dynamic
increment, and displacements of the
wall, have been highlighted.
Based on the several theoritical
and laboratory studies it was found
that the lateral earth pressure on
retaining structures is increased
during an earthquake, and the amount
of this increment depends on the magnitude
of the ground acceleration. Furthermore,
it was found that the pressure
distribution behind a retaining
wall is not linear, as it is coridered
in static case. The point of application
of the total dynamic pressure
is higher than one third of the heiqht
of the wall from its bottom, as it is
considered in static case.