TECHNICAL | DIGITAL/BIM
To link the geotechnical units of the geotechnical model with associated data sheets of the rock mass units, relative paths were given in the attributes of the volumes. The datatype of these relative paths is a ‘string’, but
– depending on the used IFC viewer – the paths can be directly used to access further .pdf files from the BIM model. To create these, relative paths are inserted starting from the location of the IFC file to linked files or folder paths. An example for a relative path to a linked drill log is
shown in Figure 8. In addition, an example of how to access a superordinate folder is shown. Figure 9 shows an exploded view of the Geotechnical Model, which consists of 17 volumes that represent
individual geotechnical units of Angath Tunnel. The topmost geotechnical units comprise the following sediments: anthropogenically modified sediments; top- soil and deposits from the River Inn; quaternary cover of the Angerberg (yellow, white and orange colours, respectively, in Figure 9 and Figure 10). Below these, several geotechnical units represent either weathered or unweathered Unterangerberg Formation (purple and dark-purple, respectively) or different zones that have been subject to tectonic deformation (orange). Additionally, 10 cross sections were generated to
provide a convenient view for pre-defined longitudinal, transverse or horizontal sections through the tunnel. In the attributes of the cross sections, relative paths to 2D section plans are added. According to Section 4.4, the Geotechnical Synthesis
Model is the representation of a classical tunnel longitudinal section. For the representation, a segmented 3D model is established with a simplified, representative tunnel shape. In individual tunnel sections, information about gas or water ingress, interface information, etc. are represented. If varying information (e.g., A, B, C, D from Figure 5)
Above, figure 8 Examples of relative links to folders or files (blue) from outgoing ifc (red)
are combined within one Geotechnical Synthesis Model, many small sections result. To avoid excessively small and complex sections, several models are created for the different data. Doing this is a trade-off between having few models with maximum of information content versus the user friendliness and readability of the whole Geotechnical Synthesis Model, which is increased if there are multiple models for different categories of information. Five such models were created for Angath Tunnel:
● Geology: consisting of nine sections with distributions of different rock mass types.
● Discontinuities: consisting of four sections with the prediction of discontinuity properties such as their orientation.
● Water: consisting of 12 sections with water ingress forecasts and predicted water pressures.
● Gas: consisting of three sections with forecasts of gas inflows.
● Swelling: consisting of two sections with forecasts of swelling phenomena.
Above, figure 9 ‘Exploded’ view of all geotechnical units of the Geotechnical Model of Angath Tunnel. Fig. 10 shows a ‘non-exploded’ version of the model
In the respective Geotechnical Synthesis Models, different attributes are added depending on the type of information. For example, the type, azimuth and angle of interfaces are defined in the model ‘discontinuities’. The Factual Data Model represents uninterpreted
facts, as discussed in Section 4.2. For the Angath Tunnel, 36 boreholes were modelled.
Above, figure 10 Rendering of the BIM ground model of Angath Tunnel with all three sub-discipline models: Geotechnical Model, Geotechnical Synthesis Model, Factual Data Model. For an ‘exploded view’ of the geotechnical model see Figure 9
20 | October 2023
For better visibility, the boreholes were modelled as cylinders of 1m-diameter. In the attributes, further information such as the start and end of drilling, water level and a link to drilling log files were given. Figure 10 shows a rendering of the BIMGM with all three sub- discipline models. The volumes of the Geotechnical Model correspond to the exploded view that is given in Figure 9.
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