Cross passage ground treatment for the Crossrail C310 Thames tunnel

This paper provides a detailed description of the ground treatments undertaken at the 4 cross passage locations on the Crossrail C310 Thames Tunnel. Information is given into the methods employed for drilling and grouting of the Seaford Chalk, interaction with the flint beds encountered, the type of grout used and the pre and post permeability values obtained. The paper will review the Chalk classification, depth of cover between the Chalk and the overlying stratigraphy, the application of the ground treatment from the surface and from within the twin tunnels reviewing any differences in the effectiveness of the techniques used. It includes details of the quantum of water encountered during the subsequent construction of the cross passages.