Unstable rock, groundwater inflow and other unforeseen ground conditions are risk factors that often lead to delays and large additional costs in connection with underground infrastructure construction work. In order to handle these risks first-rate knowledge of structural data, bedrock and soil geology, geotechnical conditions, groundwater, etc is needed.
Preliminary site investigation for underground construction is often exclusively based on drilling. Drilling provides detailed information in discrete points, but no information in between boreholes. Modern geophysical imaging techniques can map the subsurface space in 3D in a time-and cost-effective way. There are however ambiguities inherent in geophysical models that are based on inverse numerical modelling. Furthermore the parameters derived from e.g. a geoelectrical survey are not of primary interest for underground construction, like hydraulic and mechanical properties, but the geophysical model serves as a base for more or less subjective estimations of the distribution of these.
The purpose is to develop, adapt and evaluate a methodology for combined analysis of geophysical and rock technical properties in an efficient and objective manner, so it increases the opportunity for a good evaluation of rock mass and rock quality. Better rock quality predictions reduce the risk of delays, costs and litigation related to construction in rock, and reduces the risk of negative impact on the environment.