TECHNICAL | DIGITAL/BIM
resolution models for local-scale building structures and surrounding ground. For long and large buildings, like kilometres of
Unterangerberg Main Tunnel
BIM ground model outline
Tunnel Angath Wörgl
0 500 1000 1500m
tunnel, it is considered more appropriate to include the information on typical discontinuity orientation and conditions in the attributes of the model. For this reason, discontinuities like joints and faults are characterised in the subject example model by special attributes of the Geotechnical Synthesis Model, describing the typically expected conditions for each individual tunnel section.
Above, figure 6: Geographical overview map of the planned Angath Tunnel. The minimap in the upper left corner shows the project location within the Austrian federal state of Tyrol. Crosshairs show locations of exploratory drillings
also estimation of quantities, advance rates, etc. This
is a common way to document the contractual basis of expected ground conditions. The intervals of the Geotech Synthesis Model quantify
or rate the relevant geotechnical aspects. These aspects can be described in the other sub-discipline models (geological, geotechnical, hydrogeological models) which allows extraction of relevant information. This can comprise: ● expected distribution of geotechnical ground types ● discontinuity properties ● groundwater conditions ● geogenic hazards, contaminations and other aspects
Based on this condensed information with reference to the tunnel, the designer can define solutions and ‘answer’ with a design-prognosis model, including: ● planned excavation methods ● expected distribution of support types ● expected additional measures for ground improvement, health and safety, logistics, etc.
Below, figure 7: Structure of the BIM Ground Model of Angath Tunnel
Explicit geometric modelling of complex geological structures, such as discrete fracture networks (see e.g. Pan et al. (2019)), can be valuable for specific use cases (e.g., finite element modelling (FEM)) with high
BIM ground model Tunnel Angath
Factual data model
Geotechnical model
Geotechnical synthesis model
5. CASE STUDY: ANGATH TUNNEL In this section, implementation of the BIM concepts discussed above is presented for a project case study, concerning the BIMGM of the Angath Tunnel, located in the Lower Inn Valley, in the Austrian federal state of Tyrol. The rail tunnel project runs through the ‘Unterangerberg’, which is a smooth plateau that rises around 150m above the valley floor and has a maximum elevation of ~ 680m a.s.l.. The River Inn confines the Unterangerberg to the South and the nearest city to the project is Wörgl. The Angath Tunnel is on the Schaftenau – Radfeld
section of the trans-Europe rail line being developed in stages to connect Berlin to Palermo, and is also part of the northern access to the Brenner Base Tunnel. Within this route section, Angath Tunnel is a side tunnel located to the south and parallel to the main rail tunnel alignment and it is to be constructed in advance of the main tunnel tube. They are to be connected by six cross passages. A special access road to the construction site has to be built. An overview of the tunnel project, the BIMGM model
extent (see subsection 5.2) and locations of nearby exploratory drillings are given in Figure 6.
5.1. Engineering geological overview The Unterangerberg comprises geological conditions that are demanding for both the planning phase (Erharter et al., 2019) and for the excavation. The tunnel will be excavated in the bedrock of the Unterangerberg Formation (UAFm), which features a rugged bedrock surface with pronounced WSW-ENE striking gullies and ridges that are covered by glacial sediments (Poscher et al., 2008; Sommer et al., 2019). The UAFm is part of the ‘inneralpine Molasse’ and is
made of prodelta sediments, deposited into marine basins affected by synsedimentary deformation (Ortner and Stingl, 2001; Ortner, 2003). The lithology of the UAFm consists of alternating claystone/marl and sandstone layers of thicknesses varying between a few millimetres to several centimetres. The rock is therefore highly anisotropic due to the low uniaxial compressive strength of around 25MPa. It can be classified as a ‘hard soil – soft rock’ material (Kanji, 2014). The rock mass of the Unterangerberg is intersected by several zones of tectonic disturbance with increased occurrence of fault zones. Located between the bedrock and the glacial cover is a zone of heterogeneous weathering up to 35m thick (Erharter et al., 2019).
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