Geomorphological Investigations for the Channel Tunnel Terminal and Portal

Extensive geomorphological investigations of the Channel Tunnel UK portal and terminal site were commissioned by TML during 1986/87, prior to the commencement of the detailed ground investigations. These studies were primarily concerned with identifying and delimiting the spatial extent of landforms, superficial materials and in particular the evidence for contemporary or relict slope instability. The investigations took the form of large-scale (1:500) geomorphological mapping of the proposed development area. This paper describes the results of the mapping and how the information was incorporated into the site investigation and subsequent construction programme. In addition, some conclusions are drawn about the geomorphological evolution of the landslides that had developed off the chalk escarpment in the study area.