DIGITAL/BIM | TECHNICAL


3.2. The BIM ground model within the building life cycle The BIMGM is subjected to constant change and update throughout a tunnel’s life cycle and consequently also serves different use cases. Use cases in the design phase of a tunnel are, for example: compilation of existing data and knowledge within one model; route selection; visualisation and communication of complex ground conditions; coordination of different disciplines that address ground-related topics; estimation of excavation quantities; providing input for geotechnical assessments (e. g., numerical modelling); preparation of tender documents. However, the BIMGM is not only a tool for the design


phase of a project but should also serve different purposes throughout the rest of its life cycle. During construction, the BIMGM can be further used as a database for the collection and combination of the digital geological-geotechnical documentation from the excavation. It enables model-based comparison of expected versus encountered conditions with a ‘single source of information’ and thus increases the efficiency of keeping an overview of the excavation progress. During the maintenance and operational phase,


both a BIMGM from the planning phase and one that documents the ‘as-built’ state from the construction phase should be available to help identify possible ground-related damages that can occur with a long time lag (e.g., long-term settlements, fractures, unforeseen water ingress, etc.,). A future use case of BIMGMs is discussed in Erharter et al. (2022), which concerns knowledge derivation for future projects based on bigger BIM databases. Several of the cases are based on DAUB (2022). A graphical representation of use cases of the BIMGM throughout a building life cycle is given in Figure 2.


3.3. Expectations for the BIM ground model The basic requirement for the BIMGM is that its information content (geometrical and metadata) is at least the same as in conventional/ non BIM-based planning and in accordance with all current standards and guidelines. BIM-based planning should not be an end in itself but


to create an actual benefit for the tunnel. The main purpose of the BIMGM in the planning phase


of a tunnel is to ease the communication between different parties as it can serve as a central source of geological information. Based on that, everyone should be able to derive information as desired; lengthy coordination between planning companies is needed to avoid generation of error-prone plans (a discussion on the current limitations of visualisation of geological data is given in Section 6). Although geological 3D modelling has been done for


several decades, the rise of BIM has pushed geological and geotechnical 3D modelling in civil engineering. Therefore, BIM ground modelling is often expected to increase the quality of the geological prognosis. In reality, the geological 3D modelling and 3D visualisation of buildings within the geology help all involved parties to get a better understanding of complex conditions and thus increase the value of the geological model. It must be noted that geological 3D modelling can


only improve the previously mentioned aspects of a geological prognosis, and it is as dependent on the quality of the engineering geological investigation as conventional geological planning. In the context of modern tunnel construction


contracts, like Design and Build or Alliance (Deutschmann, 2021; Karasek, 2021), BIM-based planning has the advantage that it can help to communicate the totality of complex ground conditions better to


communication of complex geology


route selection Visualisation


Conceptual design


Recycling Demolition


Retrofitting Modification


knowledge derivation for future projects


Maintenance Repair


management


indentification of “ground related” building damages


Facilty Operation Billing Design options


Detailed design Coordination


visualisation of uncertainties


simulation of building - ground interaction


Simulation and analyses Cost estimation


Drawings derivation


Tendering Quantity take-off


Construction Pre-fabrication


Process simulation Progress monitoring


Logistics


operational data and geological information


predicted vs. encountered conditions comparison of combination of


digital geological documentation


geotechnical baseline model


cross section generation


Left, figure 2:


Inner circle: BIM – lifecycle modified after Borrmann et al. (2019, p.5); Outer circle: possible applications of the BIM ground model throughout the whole lifecycle of a building


October 2023


| 15


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49