DYNAMIC EARTH PRESSURES ON WALLS ROTATING ABOUT THE TOP.

There have been several bridge failures during earthquakes due to abutments moving away from the backfill at the base. The dynamic active pressure distribution behind the wall rotating about the top is non-linear and the magnitude of these pressures approaches zero at the base of the wall. Soil arching effects appear to increase the magnitude of the dynamic active pressures at the top one third portion of the wall. The dynamic pressures at the top of the backfill are non-zero and the magnitude of these surface pressures increase with increasing acceleration levels. The location of the point of application of the total dynamic active force is at 0. 55 H from the base of the retaining wall, and is independent of the input acceleration levels. Based on their experimental findings using the University of Washington shaking table, the authors propose a procedure for the design of such retaining structures in seismically active regions.