Stability and Instability of Granular Materials under Imposed Volume Changes: Experiments and Predictions

Abstract

Calculation of volume changes by constitutive models for soils and correct transition from contraction to dilation is important for prediction of undrained conditions under which developing pore water pressures may result in instability or in increased stability. Partly drained conditions involving imposed volume changes occur under many field-loading conditions, and prediction of the correct soil response is important for analysis of geotechnical structures. The effects of imposed volume changes on the instability of granular materials are studied in experiments on a fine sand in which water is forced into or out of the sand specimen during shearing. The effects on stress–strain behavior and stability are recorded and discussed. The conditions of imposed volume changes are then simulated with a single hardening constitutive model and compared with the experimental results. It is shown that the model can predict the corresponding loading paths and sand behavior as well as the resulting stable and unstable conditions.