Implementation of MWD-Data for Grouting Purposes in a Large Infrastructure Project—The Stockholm Bypass

The Stockholm Bypass is a new route for the European highway (E4) which will connect the southern and northern parts of the Stockholm County. In total over 18 km of the bypass are to be constructed in rock tunnels. The environmental permit for the project is an allowable leakage in the range of 2-5 l/min per 100 m tunnel. To meet this, continuous pre-grouting of the tunnels will be performed. However, since the geological conditions vary along the tunnel, investigation of the ground conditions ahead of the tunnel face is performed by registration of MWD-data (measurement while drilling) from the pre-grouting holes. The work flow requires that the contractor drills every second hole in a grouting fan and sends MWD-data to the client. As the contractor drills the remaining grout holes, the client evaluates the MWD-data and decides if and where additional grout holes shall be drilled. The MWD-data will provide the client with a tool to forecast ground conditions ahead of the face and, together with the results of previous grouting screens and water inflow measurements optimize the grouting works for the encountered geological conditions.