The capability to tackle and resolve the most complex geotechnical problems is a hallmark of Moretrench. So is sharing our experiences and lessons learned on those projects with the engineering community at large through technical forums such as short courses, conferences, seminars, industry websites and trade magazine articles. Recently, North American Tunneling Journal featured a particularly challenging project –how to access and repair a TBM halted deep beneath the middle of the Fraser River in British Columbia during mining of the new Port Mann Water Supply Tunnel.
Authored by Moretrench Director of Ground Freezing Joe Sopko and Behzad Khorshiji and Brian McInnes of McNally Construction, the article details the liquid nitrogen ground freezing program ultimately selected by the project team as the most viable option to stabilize the highly permeable sands and allow cutterhead access within the fast track timeframe. The ground freezing design and the difficult logistics requirements of accomplishing the freeze in a remote, underwater location are discussed.
“The Port Mann project was the first time such a freeze had been attempted in the middle of a river,” noted Sopko. “The freeze was very successful and tunneling operations resumed just eight weeks after the initial construction of the off-shore working platform.”