Liquefaction is a vital issue for the tunnel-sand pile interaction (TSPI) system under seismic excitation. Therefore the present study proposed a TSPI model for the liquefaction analysis numerically using the numerical code of Plaxis 3D under local seismic excitation. Validation results of the numerical code inform a convincing level of accuracy to ensure the analysis of the TSPI model using this code. In this research, the geometry of the TSPI model is considered smaller compared to the tunnel diameter to influence the probability of the liquefaction occurrence, and the only variable geometric dimension is the tunnel pile clear distance of the interaction zone while other geometric and material properties are considered to be the standard value. UBC3D-PLM (two yield surfaces consisting of kinematic hardening rules) constitutive model is used to ensure the liquefaction effect in the TSPI model; however, the excess pore pressure ratio exceeds the limiting value of 1 to inform the existence of liquefaction in the TSPI model. In addition, the uplift of sand is exceeded from the settlement due to liquefaction. However, further investigations such as experimental and analytical studies may have to be performed in the future to enhance the present study.