Crowning glory

Abstract

Refurbishment works involving sprayed concrete relining was considered unacceptable in preservation terms for the historic Thames Tunnel which now forms part of the London Underground. A compromise, preserving part of the structure, was reached. In this section a 20m wide, 5m thick grouted slab is being formed immediately above the tunnel using permeation grouting with microfine cement. The slab is being formed in gravels overlying London Clay. This ground treatment contract is being carried out by Soletanche using the proprietary MicroSol cement formation. Drilling and installation of tube a manchette injection pipes and grouting operations are described in detail. Stringent ground movement criteria were set.