Effect of Yield Criterion on Predicting the Arching Action Around Existing Tunnels Subjected to Surface Loading

Due to the rapid growth of urban development, on many occasions, it may be essential to have construction activities nearby or directly above existing tunnels. In this case, the amount of additional stresses reaching the tunnel becomes a point of concern. The arching action plays the main role in the stress redistributions occurring around the tunnel, and thus the amount of increase in the lining straining actions. Therefore, the goal of this paper is to study how different soil models capture the arching effect on the stress distributions around tunnels. The predicted stresses in any geomechanical problem can be highly dependent on the yield criterion of the material model used in the analysis. The paper compares between the predictions of arching using elastoplastic and poroplastic material models. The Mohr-Coulomb model is used to represent elastoplastic models. Whereas, the Modified Cam-Clay model is used as a poroplastic model. Two-dimensional plane strain models are conducted using the finite element software PLAXIS in which the Mohr-Coulomb and the Modified Cam-Clay are integrated. Although all the used models in this study are calibrated to the behavior of the same soil, different stress redistribution behavior and values are predicted for different constitutive models.