Volume Changes in Sands during Cyclic Loading

Measurements of the volume change behavior of sands under cyclic loading simple shear conditions suggest that the vertical strain due to compaction depends only on the shear strain amplitude induced in the sample at strains exceeding 0.05%. This indicates that cyclic shear strain, which deforms the sample allowing particles to move into denser packing, may well be a fundamental parameter in determining the volume change behavior of cohesionless soils under dynamic loading conditions. Quantitative data also showed that there was significantly more volume change for sand at relative densities below 60%. In addition, the importance of the first few strain cycles in determining the total vertical strain in the sample was indicated by the fact that for the range of test parameters studied, as much vertical settlement due to compaction occurs in the first 10 cycles as occurs in the next 40 cycles. The test data may be used to evaluate the possible magnitude of ground surface settlements due to ground shaking caused by earthquakes or other types of ground vibrations.