TYSSE Tunneling Test Section and Excavation Beneath Schulich Building

Abstract

Twin tunnels for Toronto Transit Commission’s (TTC’s) Toronto-York Spadina Subway Extension (TYSSE) pass directly beneath York University’s prestigious Schulich 3-
storey building. Predictions of settlements potentially associated with EPB tunneling and adjacent station deep excavation indicated that compensation grouting would be necessary to control building movements.

Based on observed settlement performance and to mitigate schedule, the contractor proposed to continue mining beneath the building foundations without compensation grouting in place. The TTC team and contractor set up an approximately 140-m instrumented test section, to confirm EPBM performance and ground response. Test section results were successful and the contractor was permitted to advance beneath the building under diligent TTC observation. The maximum recorded movement was less than 3 mm and no damage was observed.