Unified Design Approach for Rock Fissure Grouting—Best Design Practice for Pre-Grouting of Rock Tunnels in Sweden

In general, all tunneling contracts in Sweden are based on performance contracts. There has been a large increase in the knowledge and understanding during the last decades in Sweden regarding sealing of rock tunnels using mostly cementitious rock fissure grouting. This increased know-how derives from extensive research and execution of continuous pre-grouting throughout different rock tunneling works in Sweden. However, there is still a large variety in grouting designs as well as in performance between, and even, within projects. In order to make sealing of tunnels more efficient the Swedish Transport Administration has initiated a project to establish a unified design approach for rock fissure grouting in hard crystalline rock. The aim of the design approach is to have a coherent and structured process and methodology for grouting design, resulting in an appropriate, similar and transparent design approach independent of designer. The purpose is thus to introduce explicit guidelines for grouting design and its presentation as grouting classes that will be used in technical specifications, bill of quantities and prognosis for further procurement of grouting works in performance contracts. The improved tendering document should result in reduced costs due to efficient design works followed by an easier procurement process for performance contracts along with improved grouting performance and hopefully also less claims/disputes. The design approach is not yet implemented. However, the design approach is based on known theories and experience that are now compiled into one comprehensive methodology.