Construction of low-level tunnels below Waterloo Station with compensation grouting for the Jubilee Line Extension

A new station on the Jubilee Line Extension is under construction beneath the existing main line railway station at Waterloo. The complex of tunnels includes two platform tunnels at low level which are connected to higher level tunnels linking to existing London Underground stations by two banks of escalators via central concourse tunnels. Total greenfield site settlements of 200mm were predicted based on volume losses of 2%. Compensation grouting was specified to enable the maximum settlement to be reduced below 25mm. This Paper describes the performance to date of the tunnelling, grouting and structure movements.