Numerical Assessment of Subsidence and Adjacent Building Movements Induced by TBM-EPB Tunneling

Abstract

A three-dimensional (3D) numerical model simulating a twin tunnel excavated by a tunnel-boring machine (TBM)-earth-pressure balance (EPB) is presented. All relevant components are taken into account, and the influence of the parameters adopted in the TBM-EPB method on the induced ground settlements is investigated. The sensitivity to variations of the face support, the pressure applied to the steering gap slurry, and the tail gap grouting were also evaluated within the framework of parametric analyses. The effects from and on a building located at or beyond the greenfield trough width were also investigated. The greenfield volume loss at the ground surface was found to be 0.85%, increasing to 0.97% at the building foundation level. These values were further increased by 6% at the cross section where the building is located. Furthermore, a full soil-structure interaction using 3D numerical analysis was carried out to evaluate the ability of numerical methods to provide accurate displacement prognosis for buildings adjacent to tunnels excavated by the TBM-EPB method. Conclusions regarding the effects of relevant parameters, which have been drawn based on the application of the method to the ongoing Thessaloniki subway, could be useful for the future design and construction of shallow tunnels by the TBM-EPB method. (C) 2014 American Society of Civil Engineers.