Unique Design Challenges of the Central Bayside System Improvement Project Tunnel Connections and Shafts

摘要

The Central Bayside System Improvement Project is a critical element of San Francisco Public Utilities Commission's Sewer System Improvement Program, to upgrade its aging, seismically vulnerable combined sewer system. The project is comprised of small and large diameter conveyance tunnels, two deep large diameter shafts, two deep smaller diameter shafts, and several complex and challenging soil ground tun?nel connections within a network of existing infrastructure. The key design challenges include tunnel connections mined through, under, and around existing pile founda?tions and utilities located within San Francisco's Young Bay Mud and alluvial deposits. Several unique and innovative design solutions are described to address timber and steel pile obstructions, protection of sensitive utilities in a highly vulnerable seismic area.