DYNAMIC SOIL AND WATER PRESSURES DUE TO SATURATED BACKFILL ON NON- YIELDING RIGID VERTICAL WALLS

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 recognized 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 distribution of the second type is in a bulged form with a peak value at an upper section of the backfill depth. The dynamic water pressure resultants of this type for cohesive backfills are nearly as much as the value of the Westergaard's one but is applied around at 0.6 H from the bottom of soil layer. 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. (A)