The relationship between surface terrain and subsurface features has revealed a critical gap in current spatial modeling techniques. This research introduces a unified spatial data model utilizing 2D and 3D Triangulated Irregular Network (TIN) data structures. Current methods focus primarily on surface modeling, limiting the analysis of subsurface elements. To address this, we propose extending TIN-based principles into three dimensions for a comprehensive representation and analysis of both surface and subsurface objects. The goal is to develop a flexible unified spatial data model that seamlessly integrates surface and subsurface data through 2D and 3D TINs. The study outlines methodologies for creating and structuring integrated TIN-based models, encompassing algorithms for TIN generation and topology in both 2D and 3D. Initial progress includes their data structure based on 3D triangulation. Further research aims to develop accurate 3D integrated topology, topology tables, and a unified spatial data model. The research highlights the flexibility of TIN in constructing topology and emphasizes its usefulness in establishing a unified spatial data model.