A Cyclic Shear-Volume Coupling and Pore Pressure Model for Sand

A two parameter incremental shear-volume coupling equation is presented for sand. The equation is based upon experimental data and gives predictions that are in excellent agreement with data over a range of relative densities and stress conditions. Empirical expressions for the two parameters based on incorporated in a simple shear pore pressure element model and the predictions of the model are compared with both saturated undrained cyclic strain and cyclic load tests. It is found that, provided a threshold strain is incorporated, the model predictions are in very good agreement with the laboratory data over a wide range of stress and density conditions. The element model is also calibrated against field experience during earthquakes, and predicts pore pressure rise and liquefaction behavior in close agreement with current design practice. The model can easily be calibrated to represent any cyclic loading data and is appropriate for incorporation in loose coupled dynamic analyses procedures such as those employed by Finn and his colleagues