NATM/SEM Analyses for San Francisco’s Transbay Extension Tunnel
Abstract
The Transbay Downtown Extension (DTX) in San Francisco involves the construction of a large-span tunnel with a width ranging from 43 to over 60 feet. The tunnel will be excavated using the New Austrian Tunneling Method (NATM), also known as the Sequential Excavation Method (SEM), in highly fractured and sheared rock. This paper discusses the FLAC (Fast Lagrangian Analysis of Continua) analyses that were completed for conceptual design of the tunnel support system and to develop surface settlement estimates for the evaluation of measures to protect existing buildings located above the tunnel from damage.
2008
North American Tunneling Conference (NAT) Conference Proceedings
Steve Klein
Jacobs Associates
Yiming Sun
Jacobs Associates
Eileen Cooney
Jacobs Associates
