TBM (Tunnel Boring Machine) tunneling in urban areas by EPB (Earth Pressure Balance): design consideration of Hanoi pilot light metro line

Abstract

The Hanoi Metro Pilot Light Line 3 is part of the new transport system for the city. The construction works in this contract include a twin bored tunnel running parallel, with a distance ranging from 12 to 35 m. The 2.6 km twin tunnels will be bored by two 6.3 m diameter Earth Pressure Balanced Tunnel Boring Machines (EPB TBM). The correct choice of the right type of machine together with its back-up equipment is essential to ensure the success of this project. Therefore, in terms of risk analysis, the correct choice of the machine should be considered as one of the primary risk-mitigation measures for controlling the effects of the tunneling induced settlements, a possible instability or collapse of the excavation face, and securing the completion time while respecting actual advance rates. The ground condition along the tunnels mainly includes silty sand partly dense sand and gravel. Given the conditions and potential risks, this paper discusses TBM design considerations to mitigate related concerns.