Nonlinear Constitutive Soil Models for the Soil–Structure Interaction Modeling Issues with Emphasis on Shallow Tunnels: A Review

With the growing recognition of the significance of accurate soil–structure interaction (SSI) modeling in geotechnical earthquake engineering, particularly for shallow tunnels in soft soils, a comprehensive understanding of soil nonlinearity (due to the variable shear strain level) becomes critical. In this regard, this work aims to identify the capabilities of several nonlinear constitutive soil models under various loading conditions and how they can be effectively employed using the finite difference method in a three-dimensional context to implement full dynamic motion equations. Therefore, this review paper encompasses an in-depth exploration of nonlinear constitutive soil models and their utility under varying loading conditions, with a specific focus on SSI in shallow tunnels. This research also provides strategic recommendations and limitations addressing critical modeling issues in general and related to model dimensions, loading, and boundary conditions, thus offering valuable guidance for future research and applications in this field. The investigation revealed that certain models are more effective under specific loading conditions, providing new insights into how best to apply these models for accurate SSI modeling. This enhanced understanding of the capabilities of different soil models under various conditions offers invaluable guidance for future research. It also has significant implications for the practical application in geotechnical earthquake engineering, especially concerning the safety and resilience of shallow tunnels in seismic-prone regions.