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Geoinformatics-8-2008
article rep) and attribute data (links to a relational database), describing the tunnel shell and associated tunnel infrastructure like rails, piping, electric lines and emergency equipment. in the geobim environment, s_tgo and s_ngo can be related by boolean operations among the solid objects and by database queries involving the geological, hydrological, geotechnical and technical attributes. as an example, the possible impact of the shear zone (fig. 2) on the tunnel can be highlighted by a combination of boolean intersection of relevant s_go objects and a database query involving tunnel shell, tunnel infrastructure and security equipment parameters. once a consistent geobim has been established for a tunnel, maintenance work or future tunnel extensions like a parallel tube or emergency exits can be scheduled in an economic way. moreover, the s_go framework is a quantitative foundation for technical simulations like air pollution or fire propagation. figure 4: s_tgo associated with a tunnelling project (detail of fig. 0). s_ngo in front of the shear zone (here: phyllite rocks) have been switched off to view the tunnelling infrastructure. the emergency shaft s shell has been rendered transparently to visualise the interior, e.g., the stairs and the elevator shaft. see text for details. and properties of s_gos need to conform to open standards. this approach should enable engineers to build better and safer buildings, in a more efficient way. two practical geobim examples geo building information models have been developed using software from autodesk (autocad civil 3d) and bentley (microstation). tunnelling tunnelling projects involve highly complex s_ngo and s_tgo arrangements (compare figure 2 and figure 4). during tunnel planning, the building ground is thoroughly explored, yielding excellent data for the setup of the s_ngo solid model. the s_tgo, which is a state-of-the-art civil engineering by-product of the pre-project phase, holds all geometry (b- design of building pits in settled areas building projects in urban areas can be challenging because of pre-existing infrastructure. when excavating a building pit, besides geology and hydrology, all existing subsurface wiring, piping and foundations have to be considered (see figure 5). geobim, in providing the solid-based, full 3d management of relevant data, significantly reduces planning time by integrating in an optimised manner, newly-planned and existing infrastructure. moreover, the risk of damaging existing subsurface infrastructure is minimised. fritz zobl, fritz.zobl@oeaw.ac.at, robert marschallinger, robert.marschallinger@oeaw.ac.at giscience salzburg, austrian academy of sciences. www.oeaw.ac.at/giscience geobim video link: www.oeaw-giscience.org/ downloadmaterial/geobim links/ references: www.citygml.org www.citygmlwiki.org http://en.wikipedia.org/wiki/boundary_representation http://en.wikipedia.org/wiki/nonuniform_rational_bspline eastman et al., (2008): bim handbook: a guide to building information modelling for owners, managers, designers, engineers and constructors, wiley figure 5: building pit excavation in an area which was previously covered with buildings. here, geobim plays a significant role in portraying the existing infrastructure. latest news? visit www.geoinformatics.com 43 december 2008
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