Very recently the Building Information Modeling (BIM) design approach has landed in the infrastructure field, giving life to the I-BIM, the BIM for the infrastructures, including geotechnical underground works likes tunnels. In this framework, the present paper shows an application in the field of geotechnical engineering of the BIM based design approach to the case of an underground line. It is a tunnel excavated by means of traditional method, currently under construction. The project defines, in a central BIM model, a detailed tunnel structure model integrated with geological-geotechnical information for the definition of the subsoil 3D model. Once the BIM model of the tunnel stretch under study was completely defined, it was imported into a finite element (FE) model to perform deformation analyses. Thus, BIM-to-FEM-to-BIM interoperability was exploited in order to verify the maturity level of the BIM approach in the field of application for geotechnical infrastructures. Finally, the BIM fourth dimension (4D) was also implemented in the central model for the time management of the tunnel excavation process, synchronized with the numerical model. The BIM based procedure proposed in the present work can be considered as a case study in the technical literature of I-BIM for tunnels, putting in evidence limitations and advantages: i) a high level of BIM maturity was not yet achieved in the infrastructures field; ii) the BIM-to-FEM interoperability seems to be not fully effective and many operations still require the manual intervention; iii) the FEM-to-BIM interoperability brings back all geotechnical choices and hypothesis to the central BIM model, linking the models into a continuously interoperable circuit; iv) an important part of the design of civil infrastructures consists of addressing geotechnical aspects, hence the inclusion of ground conditions and geotechnical data into the BIM model can improve the quality and the usefulness of the model, not only during the design phase but also, and in particular, during the construction and the lifecycle management of the infrastructure, as a support to decision making process especially in urban context.
