Third Street Light Rail Phase 2, Central Subway Stations, San Francisco, CA-Utilization of Multiple Foundation Techniques

摘要

In October 2013, Bencor Global (a Keller Company) was awarded a subcontract by the successful prime contractor, Tutor-Perini Corporation, to perform key elements of the construction of the support of excavation system to facilitate the installation of underground subway stations for the project owned by the San Francisco Municipal Transportation Agency. The Central Subway (Contract 1300) is the second phase of San Francisco's Third Street Light Rail Program. It is a 2.74 kilometer extension that will expand light rail service within the city, improve regional connections to Caltrain, BART, Muni Metro, and provide an alternate transportation option to congested vehicular surface traffic.The key elements of this project included the utilization of three different advanced foundation techniques using diaphragm walls, compensation grouting and jet grouting at the new Chinatown Station (CTS), Yerba Buena/Moscone (YBM) and the Union Market Street Station (UMS). This paper will discuss the complexities associated with the planning and performance of geotechnical construction work in the heart of downtown San Francisco within densely populated neighborhoods and complex underground utility systems. It will also highlight the logistics associated with coordinating key elements of a complex foundation system and the benefits of utilizing one geotechnical contractor to perform all three elements on the project.