Dynamic Response of Unsaturated Soils Using Resonant Column and Bender Element Testing Techniques

The main objective of this work was to experimentally investigate the influence of key environmental factors, including compaction-induced matric suction and confining pressure, on small-strain stiffness properties of partially saturated sandy and clayey soils using the pressure plate, resonant column, and bender element testing techniques. To achieve this goal, a comprehensive series of resonant column (ASTM D 2325-68), bender element (ASTM C 778), pressure plate (ASTM D 4015-92), and filter paper (ASTM D 5298) tests were conducted on several identically prepared specimens of loose, poorly graded sand (SP) and compacted, high plasticity clay (CH) subject to different compaction-induced (post-compaction) suction and confining stress states prior to resonant column and bender element testing. Compaction-induced suctions in all specimens were assessed prior to testing via a full set of previously calibrated soil-water characteristic curves (SWCC). Compaction-induced matric suction was found to exert a significant effect on the small-strain stiffness response of partially saturated SP and CH soils both from bender element and resonant column testing techniques.