EPBM TUNNELLING IN DOWNTOWN VIENNA

This article focuses on an earth pressure balance machine (EPBM) tunneling project in Vienna, Austria. The tunnel is located in the center of the downtown area and passes directly beneath Line 1 of the U-Bahn metro with just 3m of clearance. The tunnel is a 2.6km long section of the Wien River Valley Collecting Sewer (WSKE) project. The objective of the WSKE project is to prevent further overflows and river contamination, since the LWSK and RWSK interceptors which were built in 1930 and run along the right and left banks of the Wien River, suffer from inadequate capacity. The article describes the underground geology and how the decision to use an EPBM to drive the tunnel was the best choice, particularly as it reduced the risk of uncontrolled surface settlement. It details the tunneling equipment and procedures used, and relates how a soilfrac method was used to jack up the two U-Bahn tunnels. This was done in order to protect the U1 tunnels from uncontrolled settlements and as well as ensuring that service would not be interrupted on the metro line.