This study employed an advanced elastoplastic constitutive model for sandy soils and a novel fluid-solid coupling element in Abaqus to investigate the dynamic responses of soil-utility-tunnel systems during seismic-induced liquefaction. By comparing the results of a free-field model, a single-tunnel-soil model, and twin-tunnel-soil models with simplified ground and input conditions, this study investigated the effects of soil-structure interaction (SSI) and structure-soil-structure interaction (SSSI) on the development of liquefied zones, as well as the impacts of tunnel spacing on the structural internal forces and displacement responses. The results indicate that SSSI between adjacent tunnels significantly affects the dynamic responses of the structures and surrounding soil during liquefaction. When the spacing between adjacent tunnels is relatively small, the dynamic internal forces of the tunnels during liquefaction significantly increase compared to cases without adjacent tunnels. Additionally, the uplift and rotational displacements are also higher for adjacent twin tunnels. The amplification effects of internal forces and displacements caused by SSSI gradually diminish as the tunnel spacing increases. In conclusion, in the seismic design of utility tunnels considering liquefaction, the SSSI effects should be carefully considered if adjacent tunnels or other underground structures are present, thereby avoiding the underestimation of structural responses and the corresponding safety risks.