The main purpose of pre-excavation tunnel grouting is to reduce water leakage and prevent the lowering of the ground water table. A successful sealing of rock requires thorough grouting design and accurate material selection. A detailed grouting technique - specification is also required; this should be based in parameters evaluated after a combination of pre-investigation results and scientific research (arithmetical calculations).
In Finland, there are currently no national guidelines (design principles-standards) related to rock tunnel grouting neither Eurocodes explicitly describing the process of grouting designing.
A traditional approach to define the materials and design principles of pre-grouting included the following:
Consideration of the water tightness class & geological conditions
Empirical knowledge and experiences from similar projects
Still, is this approach sufficient towards a successful result-driven implementation, also making economical sense?
The main scope of this paper is to present the grouting design methods used in urban projects in Finland so far; on this basis, the principles of a strategy that could increase the grouting efficiency, along with the designer's working processes in the future will be also presented.