This paper introduces a novel stable node-based smoothed particle finite element method (SNS-PFEM) integrated with the dual mortar contact method, designed to address fully coupled thermo-hydro-mechanical (THM) structure-soil interaction geotechnical problems, particularly those involving large deformation. The proposed SNS-PFEM framework offers three key advancements: (1) it proposes a smoothed thermal strain, enabling elastoplastic thermo-mechanical analysis in NS-FEM and SNS-FEM; (2) it presents the SNS-PFEM framework as a viable model for fully coupled THM large deformation problems; and (3) it implements the dual mortar contact method within the THM SNS-PFEM framework to effectively model structure-soil contact. The validity of this method is demonstrated through four benchmark tests, including the thermo-mechanical (TM) coupled sliding beam, the hydro-thermal (HT) coupled moving liquid, the THM coupled thermal consolidation, and the THM coupled half space heating. Additionally, the proposed THM SNS-PFEM framework is applied to investigate the interaction behavior between submarine pipelines and seabed soil during penetration and buckling, with a specific focus on thermal effects. The results reveal the competition mechanism between thermal expansion and friction degradation, and how these factors influence soil resistance, providing a promising contribution to the understanding and modeling of complex geotechnical problems.