Shear Stiffness Modeling of Cemented Sand

Nonlinear site response analyses can provide more accurate predictions of ground motions during an earthquake than equivalent linear procedures, especially for higher amplitude ground motions.However, the accuracy of the nonlinear analysis is limited by the availability and accuracy of the models used to represent the soil profile. The availability of models that represent cemented soil is very limited because the response of such soil to dynamic loading is not well understood, even though natural cementation occurs in manyseismically active areas.This research investigates the shear modulus and damping of cemented sand through laboratory tests with flush mounted transducers, bender element and resonant column devices. The effect that the cement type, cement content, void ratio, confining pressure and sand particle properties have on the reduction of shear modulus and increase in damping with increasing shear strain as well as the maximum shear modulus are examined through the test results.A new formulation modeling the nonlinearity of the stiffness of cemented sand based on the model SimSoil is proposed and evaluated with the data from this and previous studies. Model parameters are determined for different types of sand andcementation agents. The model was also implemented in a nonlinear site response analysis code, AMPLE 2000 to illustrate the influence of cementation in deposits on the site response.This research advances the understanding of cemented sands by providing a database of test results, and a model which can be used to predict the response of cemented sand to dynamic loads. This can be useful for performing site response analysis for naturally cemented sites or sites that have been improved by cementation.