... for much of its length through the Queenston Formation and will encounter mixed face conditions, blocky ground, horizontal and inclined shear surfaces, and high horizontal stresses, as well as, unique challenges such as swelling, vertically variable hydrological conditions and topographic effects beneath...

... Queenston Formation liner tunnel design shale horizontal stress southern ontario membrane investigation diffusion tunnel lining system excavation grout time-dependent deformation construction tunnel deformation Accounting for time-dependent deformation in the Niagara Diversion Tunnel...