Abstract: Although both three-dimensional (3D) geological modeling technology and building information modeling (BIM) based structural modeling technology have advanced quickly in their respective fields,there are considerable variations between them in terms of data sources,modeling techniques,and information expression.At present,the two types of models are mainly superimposed in space,and it is always difficult to integrate well.Taking geological bodies and structural bodies in geotechnical engineering as research objects,Boolean operations were applied to the two types of models,and finally a deep fusion method of 3D geological model and BIM structural model was established through plane loop search and spatial loop analysis.The overlapping relationship between geological model and structural model was recorded,and Boolean operation between the surfaces was carried out for the geological model and structural model.Based on recursive algorithm,collinear recognition was performed for line segments on the face,and new vertex,line and face information were recorded.Through plane loop search,new geometric topological relations of vertices,directed edges,directed rings and directed faces were established on the plane.The geometric topological relationship of directional surface,directional shell and directional body was formed in space by means of spatial loop analysis,and then the geometric topology reconstruction of geological and structure model was realized,so as to truly realize the deep integration of geological model and structural model.Combined with the mechanical analysis requirements,the conversion of the deeply integrated model and the mechanical analysis model was realized,which further verifies the validity and applicability of this technology.