Interceptor project sees TBM acceptance

30 June 2017


USA - The TBM for the 1.89km Ohio Canal Interceptor Tunnel has undergone factory acceptance. The 9.26m Robbins machine, a hybrid EPB / hard rock single shield machine was subsequently shipped the 40km from the factory in Solon, Ohio to the worksite in Akron.

The audience at the factory acceptance included Akron Mayor Daniel Horrigan, Robbins chief engineer Dennis Ofiara, and David Chastka, project engineer for contractor Kenny-Obayashi JV. 

The machine will be launched at a depth of 12m into 68m of soft ground before entering a 183m-long zone of partial-face shale, after this the machine will switch to hard-rock mode for the remainder of the drive, which will be through a full face of shale. Continuous probe drilling will inform the changes.

Muck removal will be achieved with a durable screw conveyor, the first flight of which is covered welded-in wear plates. The auger shaft is lined with hard facing in a crosshatch pattern, while the screw conveyor casing has been similarly lined in wear plates and hard facing.  A wear monitoring plan has been prepared for the entire drive in order to maximise efficiency in the section of more abrasive rock.

A spokesperson for Robbins added: “Unique aspects of the machine include a versatile cutterhead that will be configured with consideration for both the short soft ground section and the longer section (about 65% of the tunnel) in hard rock. A combination of disc cutters and sacrificial rippers will be used in case a cutter becomes blocked.  The required rolling torque of the disc cutters has been reduced by 25% to encourage smooth rotation in soft ground. The motors of the Crossover XRE machine have been reworked from an original EPB configuration to permit higher motor speed at reduced torque for the open mode segments of the drive.”

Tunnelling is due to begin in August 2017 and the tunnel is scheduled to be operational from 31 December 2018.