California High-Speed Rail-Connecting and Transforming California-Design Considerations for Tunnels

摘要

Construction of the proposed California High-Speed Rail system will require extensive tunneling through mountain ranges in both the north and south regions of the State. Rail alignments under consideration could require between 45 to 50 miles of tunnels that range in length from several thousand feet to over 20 miles under a cover exceeding 2,000 feet at certain locations. Challenging geologic, hydrogeologic and seismic conditions are anticipated along potential tunnel routes. Geologic conditions range from unconsolidated alluvium to strong granitic rocks; tectonically sheared and deformed rock masses; high groundwater pressures and in situ stresses; and active earthquake faults. In addition, the mountain ranges exhibit environmentally sensitive areas that will have to be protected during construction. This paper discusses the design and construction challenges associated with the tunnels in this Statewide system.