Urban EPB Tunneling in Limited Space: A Case Study of the San Francisco Central Subway Project

摘要

The San Francisco Central Subway project is a challenging modern example of urban tunnelingrnin limited space conditions. Two 6.3 m diameter Earth Pressure Balance Machines (EPBs) are excavatingrnparallel 2.5 km long tunnels under low cover and in mixed ground conditions. The small launch site situatedrnbetween an interstate and an off-ramp, highly curved tunnel alignment, and geology are particular challenges.rnThese elements required customized tunnel and machine design, from TBM shipment and assembly, to launchrnand excavation.rnThis paper discusses the project challenges and solutions at the Central Subway project, with a focusrnon TBM and continuous conveyor logistics. Requirements of the project include explosion-proof electricalrncomponents, laser-guided survey, rubber-tired supply vehicles, and machine and back-up solutions for steeprninclines and tight curves.