<p>Due to the limited capability of conventional numerical methods in representing spatially discrete information, geological borehole data are often difficult to fully utilize in excavation analyses, making it hard to accurately capture complex geological effects on excavation-induced disturbances. This paper proposes a novel refined modeling method for excavation-building coupling based on 3D geological model. Inspired by the dual-coverage concept of the numerical manifold method, this method employs a geometry and property mapping algorithm that transforms complex stratigraphic structures into computable mathematical domains and achieves accurate transfer of geological properties from geological grids to numerical grids, thereby enabling direct conversion from 3D geological model to computable numerical model. On this basis, an intelligent modeling method is further developed to realize automated coupled modeling of braced excavations and adjacent buildings. The effectiveness of the proposed modeling method is validated via a case study of a subway excavation project. Results show that, compared with conventional model, the proposed model significantly improves the simulation accuracy of excavation-induced responses, particularly for ground settlement behind long-side retaining walls and building settlement. Specifically, the MAE, RMSE, and maximum deviation for long-side ground settlement are reduced by 59.0%, 60.9%, and 61.5%, respectively, and by 17.3%, 17.4%, and 22.8% for building settlement. Stability analysis reveals that the proposed model exhibits higher sensitivity to potential instability risks. Furthermore, the proposed model enables monitoring optimization by identifying key nodes of ground settlement curves and characteristic points of building settlement contours, reducing redundant monitoring points by 43%.</p>