EPB tunnelling at the Silvertown Tunnel Project in London

The Silvertown Tunnel is a new twin-bore road tunnel under the River Thames in the east of London that increases the river crossing capacity in this area and provides enough clearance for the zero-emission double-decker buses. It is being delivered by Riverlinx CJV on behalf on Transport for London (TfL). The overall project consists of tunnel approach ramps at both portals, cut and cover tunnels, and two 1.1 km-long bored tunnel sections as well as highway connections including a new footbridge and service buildings for operating the tunnel from either end. In this article, the approach and challenges of mechanised tunnelling including the river crossing in a high-density area, with a large-diameter earth pressure balance (EPB) machine in mixed-face conditions, are presented. The Tunnel Bori selection based on the geological and geotechnical information is evaluated and compared to the experience during execution of tunnelling. In detail, the actual EPB drive is evaluated by considering the face pressure support, predicted surface settlements and planned cutterhead maintenance.