Abstract:
This paper addresses the experience designing and installing bored piles for the King’s Cross area. This
includes continuous flight auger and rotary bored piles, with a range of diameters between 600 mm and
1200 mm, reaching a maximum depth of 56 m below ground level. Existing Network Rail Thameslink
twin bored running tunnels are located directly beneath the subject plots. These tunnels have an external
diameter of 6.6 m and the crowns of the tunnels are very shallow, in some cases just 10 m below the
existing ground level. Some plots needed piles to be installed in close proximity to the tunnels, which
required additional control measures and contingency plans. Pile verticality was monitored as the tip of
each pile advanced and in-tunnel monitoring readings were verified and are presented. Lessons learned
from designing, installing and testing the piles and monitoring the tunnels are addressed in this paper.