Estimating volume loss for open-face tunnels in London Clay

Abstract

A modification to the load factor approach to estimating undrained volume loss for open-face tunnelling in London Clay is proposed. The modified approach is based on the nature of ground movement observed during construction of the Jubilee Line Extension at St James's Park and Elizabeth House for different stages of open-face shield tunnel construction and tunnelling using sprayed concrete linings, described in a companion paper. The new approach is shown to provide good estimates of the volume loss observed for open-face shield tunnelling in London Clay at Green Park and Regents Park.