A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Geotechnical Challenges of Transbay Downtown Extension Mined Tunnel
The Transbay Downtown Extension (DTX) Project is a 1.3-mile-long (2.1 km) rail extension being constructed to extend Caltrain rail service and California High Speed Rail service to downtown San Francisco. The DTX will be constructed using a combination of cut-and-cover and mined tunnel methods. The 3,200-foot-long (975 m) mined tunnel section will be 56 to 61 feet (17 to 19 m) wide and 42 feet (13 m) high, and pass beneath several existing buildings and critical utilities. The ground cover of the mined tunnel ranges from 30 to 70 feet (9 to 21 m). The tunnel will be excavated in Franciscan Complex bedrock. Highly variable rock conditions dominate over the tunnel alignment. A phased excavation sequence using SEM/NATM has been developed to construct the tunnel and control ground movements. This paper discusses some of the key geotechnical challenges faced in the mined tunnel design, including characterization of ground conditions, selection of appropriate design parameters, and evaluation of excavation and support installation sequence and surface settlements based on two- and three-dimensional numerical analyses.
Geotechnical Challenges of Transbay Downtown Extension Mined Tunnel
The Transbay Downtown Extension (DTX) Project is a 1.3-mile-long (2.1 km) rail extension being constructed to extend Caltrain rail service and California High Speed Rail service to downtown San Francisco. The DTX will be constructed using a combination of cut-and-cover and mined tunnel methods. The 3,200-foot-long (975 m) mined tunnel section will be 56 to 61 feet (17 to 19 m) wide and 42 feet (13 m) high, and pass beneath several existing buildings and critical utilities. The ground cover of the mined tunnel ranges from 30 to 70 feet (9 to 21 m). The tunnel will be excavated in Franciscan Complex bedrock. Highly variable rock conditions dominate over the tunnel alignment. A phased excavation sequence using SEM/NATM has been developed to construct the tunnel and control ground movements. This paper discusses some of the key geotechnical challenges faced in the mined tunnel design, including characterization of ground conditions, selection of appropriate design parameters, and evaluation of excavation and support installation sequence and surface settlements based on two- and three-dimensional numerical analyses.
Geotechnical Challenges of Transbay Downtown Extension Mined Tunnel
Sun, Yiming (author) / Thapa, Bhaskar (author) / Klein, Steve (author)
GeoCongress 2012 ; 2012 ; Oakland, California, United States
GeoCongress 2012 ; 3275-3284
2012-03-29
Conference paper
Electronic Resource
English
Geotechnical Challenges of Transbay Downtown Extension Mined Tunnel
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