The objective of this study was to derive e an anisotropic viscoplastic rate dependent constitutive model. The model was derived on the basis of the viscoplastic theory proposed by Kutter and Sathialingam and the yield surface function suggested by Wheeler et al. The adopted yield surface function was more consistent with the yield surface of the Taipei silty clay, compared with the existing constitutive models. The model was confirmed able to simulate the undrained stress strain response for the K0-consolidated undrained compression and extension tests. The model was also used to simulate the isotropic consolidated and K0-consolidated undrained creep test. Results show that the predicted strain from the proposed model was close to the test data. Especially the model is able to predict the tertiary creep failure when the soil is subject to high stress level.
