One directional horizontal) shaking table experiments were conducted on saturated two cohesive and one sandy backfills to investigate the dynamic water and total lateral pressures against rigid non-yielding walls during earthquakes. It was recongnized that the dynamic water pressure is generated due to two different sources.
　The first source is Westergaard-type, which is due to the flow of free water in non-deformable backfill soil skeleton and the second one is due to the deformability of backfill soil skeleton under nearly undrained condition. For highly permeable backfill soils, the first source dominates in the generation of pore pressure and the second source dominates for cohesive backfills.
　The dynamic total pressure resultants for cohesive backfills are nearly twice of the Westergaard's dynamic water pressure resultant and also applied at 0.6 H from the bottom of the soil layer. Dynamic water and total pressures and their points of application of the resultant are not significantly affected by the applied vibrating frequency and the coefficient of volumetric compressibility mυ.