DIGITAL/BIM | TECHNICAL
6. CONCLUSION AND OUTLOOK A new concept of BIM ground modelling has been presented that is based on – and in accordance with – recent developments from different international working groups. The BIMGM of the Angath Tunnel was discussed as a real-world case study of implementation of the concepts, which worked perfectly fine and the chosen software pipeline proved to be sufficiently versatile and flexible. The authors wish to emphasise that the concepts
and their implementation should be understood to be only a ‘snap-shot’ of the currently ongoing and fast developments in this field. But the paper should also serve as a guideline and example to ease entry into the world of BIM ground modelling for practitioners with limited BIM experience. Despite many efforts to push the boundaries of
BIM ground modelling, several topics can be seen as limitations of the current approach and need to be improved upon. While there are first attempts to establish the concept
of the Level of Development (LOD – see for example Borrmann et al. (2019, p.10)) for the tunnel (DAUB, 2019), there are currently no accepted standards that propose a LOD for the ground model itself. DAUB (2022) presents certain granularity levels for ground modelling but this also has yet to prove its practicability. This deficit might be connected to the comparably high degree of uncertainty in ground models and also to the fact that every ground model is unique and project specific. Nevertheless, general guidelines on this topic are desirable from a client’s perspective (for clear and assessable calls in BIMGM bids) but also from the perspective of the modelling company. Another challenge is seen in the IFC format for ground
modelling. In the current state of IFC, custom properties have to be manually defined for every project which is a process that is both laborious and error prone. Furthermore, BIMGMs that are saved as IFC files are not usable for further modelling as few geological/ geotechnical software packages can deal with it directly but rely on their own proprietary file formats. This is also problematic when BIM models should be connected to Geographical Information Systems (GIS), which are widely used in geology and the infrastructure sector but hardly ever fit for BIM implementations. Considering the (often highly praised) application of
BIM models throughout the whole life cycle of buildings (Section 3.2), it is a special question for infrastructure projects (with long planned lifetimes, of more than 100 years) whether models from the planning phase would be usable several decades later when perhaps long- term – possibly ground-related – damages may have occurred on the building. Easy visualisation of geological information on a
BIMGM is a challenge today. Although a BIMGM can contain the exact same information as a conventional 2D geological tunnel section, the information on the 2D section is more eye-catching and easily readable; information in the BIMGM must be looked for and found.
This might be a minor visualisation problem but could be the source of miscommunication and errors. It could be addressed with more advanced viewing technology that is specialised on displaying tunnel-related geological information. Another challenge is the necessary level of software
skills that BIM ground modelling demands. Standard university education hardly ever involves applied courses on geological 3D modelling, or even BIM modelling. The demand on the personnel is therefore increasing as knowledge of a whole set of software packages and possibly different programming languages is required to produce state of the art BIMGMs. The case study of Angath Tunnel demonstrates well how one has to be able to establish a whole software pipeline as there is not one single software program that can fulfill all requirements. Whereas current developments of BIM for ground
modelling often focus on the planning phase (as in this study), the coming years will show how well BIMGMs can be integrated into the construction phase of a project. It is yet to be proven that economic benefits arise when BIM models are used for automatic ‘as- planned’ versus ‘as-built’ comparisons, and that the model of the ‘planned geology’ can be easily updated with information from the excavation. Lastly, it should be noted that although there are
several needs for improvement, BIM ground modelling has benefits for the whole field of geotechnics as it forces people to establish standardised procedures for activities that, for many years, have been solved by ‘in-house’ or custom solutions. The high degree of standardisation that BIM demands should be seen as an opportunity to make geotechnics more transparent and comprehensible and thus improve the industry’s standards as a whole.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Data availability A link to the data was shared at the Attach Files step and within the Supplementary material section of the paper. Appendix A. Supplementary data Attribute_list.pdf and BIMGM.ifc can be downloaded from: Link to TU Graz Repository (https://doi. org/10.3217/007z6-7sh07) Open Access This is a slightly abridged and. Edited version of the full paper published online in Tunnelling and Underground Space Technology (incorporating Trenchless Technology Research) 135 (2023) 105039, under a Creative Commons (CC) licence.
https://doi.org/10.1016/j.tust.2023.105039 Received 25 July 2022; Received in revised form 9 January 2023; Accepted 5 February 2023, Available online 15 February 2023
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