This paper presents the steel tunnel–sand–pile interaction (TSPI) response under scaled (0.05[ ]g and 0.1[ ]g) seismic excitations (Kobe and Loma Prieta) and sinusoidal wave (frequencies of 1, 5, and 7[ ]Hz) along with the sand relative densities of 48% and 80%. For this reason, a scaled shake table test was performed in the laboratory, and the 3D numerical analysis was performed by the Plaxis for the simulation. No joint was considered along the length of the tunnel to avoid complexity. In most cases, the excess pore pressure ratio exceeds the unit value at bottom and top locations of the TSPI model to inform the occurrence of liquefaction. Maximum lateral and translational displacements of the tunnel were found to be 143[ ]mm and 72[ ]mm, respectively, at the crown. In addition, the maximum vertical translation of sand and root mean square (RMS) value of the pile strain were obtained to be 61[ ]mm and 20[ ][ ]m/m, respectively. However, close variations of numerical and experimental studies may convince the accuracy of the simulation. By the way, it has a scope to enhance this study in the future by varying the geometry of the TSPI model.

Nonlinear time‐history analysis can be used to determine the liquefiable behaviors of the tunnel–sand–pile interaction (TSPI) model with the consideration of sand anisotropy. This study presents the nonlinear response of the TSPI model with the existence of liquefaction under seismic excitation. The analysis reveals that tunnel and pile behave as isotropic elements, while sand shows isotropic, orthotropic, and anisotropic characteristics. Three constitutive models including UBC3D‐PLM (two yield surfaces associated with the hardening rule), NGI‐ADP (yielding with associated plastic potential function), and a user‐specified constitutive model are adopted to evaluate the isotropic, orthotropic, and anisotropic behaviors of sand. On this basis, two finite element‐based codes (ETABS 18.1.1 and Plaxis 3D) are used to evaluate sand behaviors and responses. Responses of the tunnel, sand, pile, and excess pore pressure ratio are recorded in the interaction zone by varying the pile diameter, tunnel diameter, and tunnel–pile clearance. Compared with the orthotropic and isotropic conditions, lower variations of results are found in the anisotropic condition, except for the case of generation of excess pore pressure. In addition, the present reanalysis results are in agreement with previous analytical and case study results, which further indicates the effectiveness of the finite element‐based numerical codes.