Efficient communication of geologically related data and 3D models in tunneling projects

During the design and the construction of a tunnel there is a constant need for updated geological/rock mechanical models, often visualized in specific software within the geological discipline. Tunnel design engineers handle the design in CAD software. Often there is a communication issue between those two disciplines. The GeoBIM concept is developed for efficient communication of any geo-related underground space data. The aim is to constantly supply all team members with quick access to the same data and models at the same time. The core of the GeoBIM concept is an efficient and flexible database that can import any data in any format and make it easily accessible. From the database data can be exported for further use. Within the GeoBIM concept it is possible to publish full 3D models, which is all navigable by using only the web browser. The GeoBIM concept is exemplified by two large Swedish tunnels. more efficient and quality assured than today and ease communication with other engineering disciplines related to urban underground infrastructure. This paper’s aim is to clarify the need for better communication tools in the tunneling, geotechnical and the infrastructure design discipline and to suggest several solutions and ways forward on the aforementioned issues. We present a few examples where the GeoBIM concept has facilitated and provided better environment for which this communication has successfully been done. 2 GEOTECHNICAL MODELLING HINDERS AND REQUIREMENTS The everyday mission for the geologist and the geotechnical engineer is to find out and in the best possible way define and describe what the underground space looks like, i.e. mechanical properties and geometry, and is sometimes called geotechnical modelling. In this work, a lot of data is handled, and several different software used. It is not uncommon that the number of methods used exceeds one hundred, including core drilling and sampling, hydraulic tests, geophysical surveys such as ERT, seismics and GPR, environmental sampling and testing, hydrogeology and geotechnical laboratory testing, and others. One of the biggest challenges is to make use of all the data available during the interpretation and the modelling stages. In Scandinavia, since the early 1990’s, there is a standardized data format (SGF, 2012) used for geotechnical sampling and sounding data. The usage of this format makes it almost straightforward and convenient to handle and jointly interpret these data types, regardless of which drill rig or data collection unit is used. However, with most of the methods used, data and models are far from standardized and bringing different data types together is a challenging and often time-consuming task. Therefore, it is common that the full potential of the combined data set is not reached, or simply formulated: there is a communication issue. The traditional way of joint interpretation includes numerous drawings, plots, diagrams and tables, spread on desktops, walls, floors, screens, etc. In the digital world that has evolved during the last 10 years, many new opportunities for joint interpretation have opened. With the BIM requirements in infrastructure design, including also underground data and models, flying around the globe, the industry driven initiatives showing the potential of communicating for example geophysical data and interpretations in 3D models together with designed facilities are being brought to spotlight. The GeoBIM concept is one of those tools capable of integration, joint interpretation and visualization of all aforementioned. In project meetings, application of this concept has clearly shown to help clients and other stakeholders to understand the great potential of geophysics for reaching a proper 3D geo-model. An example of the tool used to acquire geophysical data (seismic) and final results obtained integrated in GeoBIM with different geo-data and models from Varberg railway tunnel site in south Sweden is shown in Figure 1. 2.1 Existing data formats The most widely spread standards for geotechnically and rock investigation related data are the AGS format for geotechnical and geoenvironmental data (www.ags.org.uk) and the LAS data format for geophysical borehole logging data (CWLS). In Scandinavia and the Baltic countries, the data format for geotechnical sounding and sampling defined by the Swedish Geotechnical Society is widely used (SGF, 2012). For seismic data, official standard data exchange format is the SEGY format (Norris and Faichney, 2001). However, seismic acquisition equipment commonly uses the SEG2 format, or in the case of modern seismic equipment, improved data acquisition formats (offering more header information and capability to record important data acquisition information) such as SEGD (see examples in Malehmir et al. (2015) or Brodic et al. (2015)). Once the data format hinders mentioned above are overcome within the tunneling discipline itself, a more efficiently closed digital process would be reached. With this, the possibilities for better joint interpretation and generation of the most probable geo-model, including both geometry and properties of the underground space in 3D, would drastically increase. Figure 1. Integration of different data using GeoBIM for theVarberg 6 km railway tunnel project, Sweden. Photo showing a state-of-the-art digital-based seismic landstreamer (Brodic et al., 2018; Malehmir et al., 2018) used for data acquisition (UL). Rock coverage for current tunnel design (UR), geophysical profiles (seismics and DCIP) (LL) and fracture zones, core drillings, seismic profile and top of bedrock mod-