Constructing in rock will always involve unforeseen rock conditions. This involves a large risk to a project and can in the end entail delays and extra costs. To minimize the risks, an optimized pre-investigation program has to be conducted where essential information is gathered in order to make the best decisions throughout the construction project. In this work the main focus has been on the applicability of geoelectrical methods as a tool for predicting geological and rock mass conditions. The application of the geoelectrical methods at different scales has been used to provide useful information at different stages of rock tunnel construction. In the geological setting at the Hallandsås Horst, Sweden, the method indicate fractured, water bearing rock, weathered rock and to some extent lithology changes in crystalline bedrock. Large scale geoelectrical imaging is useful in the design/production planning stage and in the construction stage. Geoelectrical methods may be combined with other geophysical methods in borehole logging and be applied late in the design/production planning stage. Additionally, borehole geophysics is important for in situ correlation/verification of the large-scale geoelectrical data.
Construction in rock is associated with risks as the knowledge of the geology and ground conditions usually is limited. Unforeseen rock conditions involve a large risk to the project and can in the end entail delays and extra costs. To minimize the risks, a profound and optimized pre-investigation has to be conducted where the necessary information is gathered in order to make the best decisions throughout the construction project (Baynes et al., 2005; Ngan-Tillard et al., 2010). Different geophysical methods are important in these investigations. In this research the main focus is on the applicability of the geoelectrical method as a tool for predicting geological and rock mass conditions.