Design and Construction Challenges of SEM Construction in Urban Area: Chinatown Station, San Francisco, CA

Synopsis:

Sequential Excavation Method (SEM) is being used more and more in urban settings in soft ground, mixed ground conditions, low cover, and overbuilt conditions for the creation of tunnels, station caverns and cross passages. To enable open face excavation, various methods of ground improvement are used in conjunction with a rigorous instrumentation and monitoring system and remedial measures to be implemented as needed. The paper examines approaches being used for the implementation of SEM tunnelling in urban areas with discussion on the impact on existing facilities, ground improvement measures, instrumentation and monitoring, and risk mitigation measures. These aspects will be illustrated through the recently completed Chinatown Station in San Francisco, California, USA.

2021 Transportation Association of Canada (TAC) Conference Proceedings
September 20 – October 1, 2021, Toronto, Canada (Munfah, N., Gall, V.)
Copyright holds Transportation Association of Canada (TAC). Full proceedings volumes can be found on website at www.tac-atc.ca.