This article presents a concept for a digital ground model usable throughout all project phases and visualizes causalities between geological conditions and the tunnel structure. Specifically, a dynamic modeling approach is introduced to represent the geological conditions from design to construction. Three process phases are dealt with: (i) a preliminary phase defining the model area, (ii) the geological prognoses, including parameterization and schematization along the alignment as a base for further planning steps, and (iii) the creation of a cumulative tunnel construction model. A schematic, parameterized, small-scale tunnel excavation element model is the basis for a dynamic adaptation of geology. In addition, detailed predictions modeled along the alignment are introduced to represent the predicted geology in higher detail, adjustable in the event of changes, and thus represent the current geological information in the construction area. These models form the basis for a tender model and a digital tunnel construction framework plan.
In conventional and mechanized tunneling, face stability is one of the constantly prevailing questions relevant to tunneling. Different tunneling methods, unique construction methods, support elements, and varying work steps are required depending on the geological conditions to achieve and maintain tunnel safety standards. The framework conditions from geology, geotechnics and tunneling and their tunneling relevant parameters contribute to developing and preparing a combined tunneling framework plan (Austrian Society for Geomechanics 2010).
Model-based design, based on – and in interaction with – a valid ground model, as part of an infrastructure information model (iiM) as a holistic, interdisciplinary and up-to-date representation of the tunnel structure in the form of a digital twin, facilitates the answer to the initial question (Flora et al. 2020). Furthermore, the progressing application of BIM in tunnel and infrastructure design (Tunnel Information Modelling - TIM), shows that there are still limits to implementing the BIM method. Implementing the digital twins and its defined goals, which further depend on its definition, is not always satisfactory.
