Monotonic, Cyclic, and Post-Cyclic Shear Response of a Gravelly Sand

Soil softening and soil liquefaction have long been a significant aspect of seismic risk, including at sites with gravelly soils. However, the performance of gravelly soils during and after earthquake events is still not well understood. A prototype large-size cyclic simple shear (CSS) device is used in this research to perform monotonic and cyclic shear tests of a gravel, a sand, and a gravelly sand mixture to evaluate the shear response of these materials. The importance of vertical strain control on constant volume behavior is also investigated for a uniform gravel material. Comparisons are made between monotonic, cyclic and post-cyclic shear response of a gravelly sand to show the relationship between these different loading conditions. The results of these tests showed that the same ultimate state line (friction angle) is attained for this material from both monotonic and post-cyclic loading.