Analysis of ground surface settlement induced by a large EPB shield tunnelling: a case study in Beijing, China.

Large size shield tunnels have been constructed with the increasing demands, because it offers cost efficiency in urban areas. One major problem created by shield tunnelling is that ground settlement occurs, which is crucial to existing structures. A detailed case study of surface settlement induced by the operation of a large-diameter earth pressure balance (EPB) shield tunnel in Beijing was presented. This study provides important new insights into the values of settlement trough parameters of empirical methods. The narrower transverse settlement trough was observed in large size tunnels. The development of longitudinal settlement can be divided into four stages, and methods were further proposed to assess the associated four components of volume loss. Results demonstrate that the proposed methods can efficiently predict the volume loss and the associated ground settlement within a reasonable accuracy by comparing with the collected field observations. In addition, a bandwidth of achievable surface settlement for future large EPB shield tunnels is suggested via performing analysis on real settlements. [ABSTRACT FROM AUTHOR]